Co-reporter:Xue Li, Lusheng Zhu, Yunlei Zhou, Huanshun YinShiyun Ai
Analytical Chemistry 2017 Volume 89(Issue 4) pp:
Publication Date(Web):January 23, 2017
DOI:10.1021/acs.analchem.6b04184
A novel photoelectrochemical (PEC) assay is developed for sensitive detection of protein kinase A (PKA) activity based on PKA-catalyzed phosphorylation reaction in solution and signal amplification strategy triggered by PAMAM dendrimer and alkaline phosphatase (ALP). In this strategy, it is noteworthy at this point that PKA phosphorylation was achieved in solution instead of on the surface of the electrode, which has advantages of the good contact in reactants and simple experimental procedure. For immobilizing the phosphorylated peptide (P-peptide) on electrode surface, graphite-like carbon nitride (g-C3N4) and titanium dioxide (TiO2) complex is synthesized and characterized, which plays a significant role for TiO2 conjugating phosphate groups and g-C3N4 providing PEC signal. Subsequently, PAMAM dendrimer and ALP can be captured on P-peptide and TiO2/g-C3N4 modified ITO electrode via interaction between the -COOH groups on the surface of PAMAM dendrimer and the -NH2 groups of peptide and ALP, which can lead to the increase of ALP amount on the modified electrode surface assisted with the PAMAM dendrimer. As a result, the amount of ALP catalyzes of L-ascorbic acid 2-phosphate trisodium salt (AAP) to produce electron donor of ascorbic acid (AA), resulting in an increased photocurrent. The proposed detection assay displays high selectivity and low detection limit of 0.048 U/mL (S/N = 3) for PKA activity. This biosensor can also be applied for the evaluation of PKA inhibition and PKA activity assay in cell samples. Therefore, the fabricated PEC biosensor is potentionally well in PKA activity detection and inhibitor screening.
Co-reporter:Jiazhuo Xie;Kun Zhang;Zhou Wang;Qinghua Zhao;Yuechao Yang
Iranian Polymer Journal 2017 Volume 26( Issue 11) pp:811-819
Publication Date(Web):27 October 2017
DOI:10.1007/s13726-017-0561-x
The continuously increasing plastic wastes and diminishing fossil resources have attracted global attention into research and development of biodegradable packaging materials. In the present study, organophilic layered double hydroxides (OLDH) intercalated with aliphatic long-chain molecules as reinforcing agents were incorporated into biodegradable poly(vinyl alcohol) (PVA) matrix by a solution casting method. FTIR, XRD and SEM were performed to analyze the structure of PVA/OLDH films. The OLDH nanosheets were well-dispersed in PVA matrix and formed strong interfacial interactions with the PVA chains, leading to remarkable improvements of optical property, mechanical performance, water vapor barrier property and thermal stability. At a loading of only 2% OLDH in PVA, we observed ~67% decrease in haze and ~66% increment in tensile strength in the composite film compared with pure PVA film. Furthermore, a 24.22% decrease in water vapor permeability (enhancement in water vapor barrier property) due to the addition of 0.5 wt% OLDH and enhanced thermal stability could be observed. These results revealed that the overall performance could be improved by introducing OLDH at very low loadings and that the PVA nanocomposite films have potential for future application in packaging films. Therefore, the use of high-performance PVA/OLDH nanocomposite films can evidently promote the application of biodegradable PVA materials in packaging industry.
Co-reporter:Haiyan Wang, Qihai Zhang, Huanshun Yin, Minghui Wang, Wenjing Jiang, Shiyun Ai
Biosensors and Bioelectronics 2017 Volume 95(Volume 95) pp:
Publication Date(Web):15 September 2017
DOI:10.1016/j.bios.2017.04.006
•A photoelectrochemical strategy is developed for methylated RNA detection.•The anti-m6A antibody is utilized to improve detection specificity.•Graphite-like C3N4/CdS quantum dots heterojunction was used as photoactive materials.•The photoelectrochemical immunosensor was validated for detecting m6A content in the blood serum of breast cancer patients.N6-methyladenosine (m6A) is an enigmatic and abundant internal modification in eukaryotic messenger RNA (mRNA), which could affect various aspects of RNA metabolism and mRNA translation. Herein, a novel photoelectrochemical (PEC) immunosensor was constructed for m6A detection based on the inhibition of Cu2+ to the photoactivity of g-C3N4/CdS quantum dots (g-C3N4/CdS) heterojunction, where g-C3N4/CdS heterojunction was used as photoactive material, anti-m6A antibody as recognition unit for m6A-containing RNA, Phos-tag-biotin as link unit and avidin functionalized CuO as PEC signal indicator. When CuO was captured on electrode through biotin-avidin affinity reaction and then treated with HCl, Cu2+ could be released and CuxS would be formed based on the selective interaction between CdS and Cu2+, leading the photocurrent obviously decreased. Under the optimal detection conditions, the PEC biosensor displayed a linear range of 0.01–10 nM and a low detection limit of 3.53 pM for methylated RNA determination. Furthermore, the developed method could also be used to detect the expression level of m6A methylated RNA in serum samples of breast cancer patient before and after operative treatment. The proposed assay strategy has a great potential for detecting the expression methylation level of RNA in real sample.Download high-res image (185KB)Download full-size image
Co-reporter:Huanshun Yin, Haiyan Wang, Wenjing Jiang, Yunlei Zhou, Shiyun Ai
Biosensors and Bioelectronics 2017 Volume 90(Volume 90) pp:
Publication Date(Web):15 April 2017
DOI:10.1016/j.bios.2016.10.066
•An electrochemical immunosensor was fabricated for N6-methyladenosine detection.•Ag@SiO2 was prepared and used as signal amplification label.•Phos-tag-biotin played a vital role of “bridge” to link m6ATP and Ag@SiO2.•The developed method was validated for detect m6A content in human cell lines.N6-methyladenosine (m6A), a kind of RNA methylation form and important epigenetic event, plays crucial roles in many biological progresses. Thus it is essential to quantitatively detect m6A in complicated biological samples. Herein, a simple and sensitive electrochemical method was developed for m6A detection using N6-methyladenosine-5′-triphosphate (m6ATP) as detection target molecule. In this detection strategy, anti-m6A antibody was selected as m6A recognition and capture reagent, silver nanoparticles and amine-PEG3-biotin functionalized SiO2 nanospheres (Ag@SiO2) was prepared and used as signal amplification label, and phos-tag-biotin played a vital role of “bridge” to link m6ATP and Ag@SiO2 through the two forms of specific interaction between phosphate group of m6ATP and phos-tag, biotin and streptavidin, respectively. Under the optimal experimental conditions, the immunosensor presented a wide linear range from 0.2 to 500 nM and a low detection limit of 0.078 nM (S/N=3). The reproducibility and specificity were acceptable. Moreover, the developed method was also validated for detect m6A content in human cell lines. Importantly, this detection strategy provides a promising immunodetection platform for ribonucleotides and deoxyribonucleotides with the advantages of simplicity, low-costing, specificity and sensitivity.
Co-reporter:Huan-Shun Yin, Bing-Chen Li, Yun-Lei Zhou, Hai-Yan Wang, Ming-Hui Wang, Shi-Yun Ai
Biosensors and Bioelectronics 2017 Volume 96(Volume 96) pp:
Publication Date(Web):15 October 2017
DOI:10.1016/j.bios.2017.04.049
•A sensitive fluorescence biosensor was fabricated for miRNA-21 detection.•DNA strand displacement reaction and Mg2+-dependent DNAzyme cleavage strategy was employed.•The developed method showed wide linear range from 1 fM to 50 pM and low detection limit of 0.27 fM.•This method can be applied to analysis the expression level of miRNA-21 in gastric cancer cell.MicroRNAs have been involved into many biological processes and are regarded as disease biomarkers. Simple, rapid, sensitive and selective method for microRNA detection is crucial for early diagnosis and therapy of diseases. In this work, sensitive fluorescence assay was developed for microRNA-21 detection based on DNA polymerase induced strand displacement amplification reaction, Mg2+-dependent DNAzyme catalysis reaction, and magnetic separation. In the presence of target microRNA-21, amounts of trigger DNA could be produced with DNA polymerase induced strand displacement amplification reaction, and the trigger DNA could be further hybridized with signal DNA, which was labeled with biotin and AMCA dye. After introduction of Mg2+, trigger DNA could form DNAzyme to cleave signal DNA. After magnetic separation, the DNA fragment with AMCA dye could give fluorescence signal, which was related to microRNA-21 concentration. Based on the two efficient signal amplifications, the developed method showed high detection sensitivity with low detection limit of 0.27 fM (3σ). In addition, this fluorescence strategy also possessed excellent detection specificity, and could be applied to analyze microRNA-21 expression level in serum of cancer patient. According to the obtained results, the developed fluorescence method might be a promising detection platform for microRNA-21 quantitative analysis in biomedical research and clinical diagnosis.Download high-res image (167KB)Download full-size image
Co-reporter:Nan Wang, Hai Fan, Jianchao Sun, Zhenwei Han, Jing Dong, Shiyun Ai
Carbon 2016 Volume 109() pp:141-148
Publication Date(Web):November 2016
DOI:10.1016/j.carbon.2016.08.004
Fluorine-doped carbon nitride (FC3N4) quantum dots were successfully synthesized on a large scale by a facile ethylene glycol-assisted ultrasonic method using bulk FC3N4 powder as the precursor and ethylene glycol as the solvent. Characterization results show that high-quality FC3N4 quantum dots with a uniform size of 1.5–2.0 nm were successfully prepared in ethylene glycol. Ethylene glycol is found to play an important role in the synthesis of quantum dots. Doping of fluorine in C3N4 could adjust the band gap structure of C3N4, resulting in altering the emission peak position and increasing the fluorescent intensity. The as-prepared FC3N4 quantum dots in ethylene glycol show much higher fluorescent intensity with the quantum yield of 39.03%. The prepared FC3N4 quantum dots were successfully applied as a fluorescent probe for bacterial imaging.
Co-reporter:Hai Fan, Nan Wang, Yijun Tian, Shiyun Ai, Jinhua Zhan
Carbon 2016 Volume 107() pp:747-753
Publication Date(Web):October 2016
DOI:10.1016/j.carbon.2016.06.082
Graphitic carbon nitride (g-C3N4), composed of only non-metallic elements, possesses a graphene-like structure and an appropriate band gap around 2.7 eV. It is finding its promising applications in sustainable chemistry. In this paper, highly ordered laminated porous carbon nitride nanostructures (OLP-C3N4) are successfully prepared via a novel two-step hydrothermal-calcination method using acetic acid as the order-inducing agent and pore-forming agent. Acetic acid and melamine are first hydrothermally synthesized to form a solid precursor. Then, the precursor is calcinated to obtain the product. The electrostatic interaction existed between acetic acid and melamine in water during the hydrothermal process is considered to play a key role on the formation of layered nanostructures. While, carboxyl group in acetic acid is favorable for the porous structure of the products. The prepared carbon nitride nanostructures exhibit high surface area and show excellent electric transport and optical properties, which may have wide applications in catalytic, adsorptive and battery materials fields. This work opens a novel way for the preparing hierarchical porous materials with unique properties.
Co-reporter:Xue Li, Yunlei Zhou, Yan Xu, Huijie Xu, Minghui Wang, Huanshun Yin, Shiyun Ai
Analytica Chimica Acta 2016 Volume 934() pp:36-43
Publication Date(Web):31 August 2016
DOI:10.1016/j.aca.2016.06.024
•A novel photoelectrochemical biosensor is fabricated for kinase activity assay.•Phosphorylated g-C3N4 is used as the photoelectric conversion material with visible-light activity.•The high affinity between Zr4+ and the phosphate group causes the assembly of P-g-C3N4 on the substrate peptide.•The developed method can be applied to detect kinase in real samples.Protein kinases are general and significant regulators in the cell signaling pathway, and it is still greatly desired to achieve simple and quick kinase detection. Herein, we develop a simple and sensitive photoelectrochemical strategy for the detection of protein kinase activity based on the bond between phosphorylated peptide and phosphorylated graphite-like carbon nitride (P-g-C3N4) conjugates triggered by Zr4+ ion coordination. Under optimal conditions, the increased photocurrent is proportional to the protein kinase A (PKA) concentration ranging from 0.05 to 50 U/mL with a detection limit of 0.077 U/mL. Moreover, this photoelectrochemical assay can be also applied to quantitative analysis of kinase inhibition. The results indicated that the IC50 value (inhibitor concentration producing 50% inhibitor) for ellagic acid was 9.1 μM. Moreover, the developed method is further applied to detect PKA activity in real samples, which contains serum from healthy person and gastric cancer patients and breast tissue from healthy person and breast cancer patients. Therefore, the established protocol provides a new and simple tool for assay of kinase activity and its inhibitors with low cost and high sensitivity.
Co-reporter:Dandi Zhou, Min Wang, Jing Dong, Shiyun Ai
Electrochimica Acta 2016 Volume 205() pp:95-101
Publication Date(Web):1 July 2016
DOI:10.1016/j.electacta.2016.04.101
•Th-mpg-C3N4 was synthesized for the first time.•Mpg-C3N4 is more suitable than g-C3N4 to fabricate the immunosensor.•Mpg-C3N4 possesses relatively large specific surface area and abundant active sites.•The immonusensor realized the sensitive detection of ALVs-J.The rapid and sensitive detecting technique for subgroup J of avian leukosis viruses (ALVs-J) needs to be developed as soon as possible in order to not only reduce economic losses but also ensure the food safety. In this paper, a novel electrochemical immunosensor was built based on mesoporous graphitic carbon nitride (mpg-C3N4). Mpg-C3N4 was used as the sensor platform to bond with the primary antibodies (Ab1). The compound of thionine and mpg-C3N4 (Th-mpg-C3N4) was synthesized for the first time to serve as the electroactive probe as well as the carrier of secondary antibodies (Ab2). Compared to bulk g-C3N4, mpg-C3N4 possesses larger specific surface area, smaller electrochemical resistance and abundant active sites. So the proposed electrochemical immunosensor exhibited amplified detective signals which realized the sensitive detection of ALVs-J. Under the opitimized conditions, the immunosensor exhibited outstanding analytical performance for the detection of ALVs-J whose titer ranged from 102.08 to 104.0 TCID50/mL (TCID50: 50% tissue culture infective dose) with a low detection limit of 120 TCID50/mL (S/N = 3). The sensitivity of the immnosensor was 6.15 μA/(TCID50/mL). This high sensitive immunosensor also displayed good selectivity, reproducibility and stability. Last but not least, this new strategy may be of great promise for clinic application in the future.
Co-reporter:Zhengbin Tian, Qingyang Li, Juying Hou, Yan Li and Shiyun Ai
Catalysis Science & Technology 2016 vol. 6(Issue 3) pp:703-707
Publication Date(Web):23 Dec 2015
DOI:10.1039/C5CY01864A
The selective hydrogenation of cinnamaldehyde and citral was investigated over platinum catalysts supported on Fe-based layered double hydroxides and derived mixed metal oxides. Among the catalysts, Pt/ZnFe-LDH showed the best activity and selectivity for the hydrogenation of CO bonds in cinnamaldehyde, and citral was mostly transformed into citronellol over the Pt/NiFe-LDH catalyst.
Co-reporter:Juying Hou, Guangjuan Dong, Zhengbin Tian, Jiutian Lu, Qianqian Wang, Shiyun Ai, Minglin Wang
Food Chemistry 2016 Volume 202() pp:81-87
Publication Date(Web):1 July 2016
DOI:10.1016/j.foodchem.2015.11.134
•A novel dichlorvos sensor was developed using carbon dots.•The carbon dots are obtained by simple and green hydrothermal reaction of feather.•The sensor was based on the fluorescence quenching effect of Cu(II) of carbon dots.•Thiocholine can restore the fluorescence of carbon dots-Cu(II) system.•The sensor shows a low detection limit and good selectivity.In this paper, a simple and sensitive fluorescent sensor for dichlorvos was first constructed based on carbon dots-Cu(II) system. These carbon dots were obtained by simple hydrothermal reaction of feather. The fluorescence of these carbon dots can be selectively quenched by Cu2+ ion. When acetylcholinesterase and acetylthiocholine were introduced into the system, thiocholine came into being, which can react with Cu2+ ion and restore the fluorescence of the system. The reaction mechanism between Cu2+ ion and thiocholine was confirmed by X-ray photoelectron spectroscopy. As one kind of acetylcholinesterase inhibitor, organophosphorus pesticides can be detected based on this sensing system. As an example of organophosphorus pesticides, dichlorvos was detected with a linear range of 6.0 × 10−9–6.0 × 10−8 M. This sensing system has been successfully used for the analysis of cabbage and fruit juice samples.
Co-reporter:Xue Li, Zhipeng Xie, Wei Wang, Yunlei Zhou, Huanshun Yin, Zhiqing Yang and Shiyun Ai
Analytical Methods 2016 vol. 8(Issue 13) pp:2771-2777
Publication Date(Web):07 Mar 2016
DOI:10.1039/C5AY03397G
The DNA isothermal amplification cycle is an effective expansion strategy, which can overcome the inherent limitation of the target to signal ratio of 1:1. In this work, we fabricated an electrochemical biosensor for the rapid detection of Dam methyltransferase activity based on the exonuclease III (Exo III) assisted isothermal amplification cycle. First, double stranded DNA (ds-DNA) containing the symmetric sequence of 5′-GATC-3′ was immobilized on the magnetic bead surface. After the ds DNA was methylated by Dam MTase, it could be further cleaved by DpnI and formed a blunt end, which could lead to the digestion of a DNA strand by Exo III and release of a target single stranded DNA (ts-DNA). Then, the ts-DNA can further hybridize with DNA probes (DNA3) immobilized on the AuNPs/Au electrode surface and form a blunt end DNA–DNA duplex. Subsequently, the DNA3 in the DNA–DNA duplex can be digested by Exo III and release ts-DNA. The released ts-DNA can further hybridize with the unhybridized single stranded DNA (ss-DNA) and an isothermal amplification cycle is achieved. The method showed high sensitivity with a low detection limit of 0.031 unit per mL. Moreover, inhibition investigation indicates that Dam MTase activity can be inhibited by using 5-fluorouracil with an IC50 value of 131.22 μM.
Co-reporter:Juying Hou, Zhengbin Tian, Huizhi Xie, Qingyuan Tian, Shiyun Ai
Sensors and Actuators B: Chemical 2016 Volume 232() pp:477-483
Publication Date(Web):September 2016
DOI:10.1016/j.snb.2016.03.092
•A novel FRET dichlorvos sensor was constructed using quaternized carbon dots.•The quaternized carbon dots possessed a quantum yield as high as 34.2%.•The FRET sensor was developed based on traditionally colorimetric Ellman’s test.•The sensor showed a low detection limit, wide detection range and good selectivity.•This FRET sensing system was adaptable for automated analyzers.Here we first reported an ultrasensitive fluorescence resonance energy transfer (FRET) biosensor of dichlorvos based on carbon dots and the traditionally colorimetric Ellman’s test. In Ellman’s test, the absorption intensity of 5-thio-2-nitrobenzoic acid anion (TNB−) at 412 nm can be used for the determination of acetylcholinesterase (AChE) and its inhibitor. We chose TNB− as energy acceptors to construct a FRET sensing system of AChE and its inhibitor. Quaternized carbon dots (Q-CDs) were chosen as energy donors to form an effective FRET system. By a two-step synthetic method, the Q-CDs with high quantum yield (34.2%) were successfully prepared. Experimental results showed TNB− can quench the fluorescence of Q-CDs to a large extent, which indicated an effective FRET between Q-CDs and TNB− was successfully established. As the inhibitor of AChE and common organophosphorus insecticide, dichlorvos can be detected using this sensing system. Under optimal conditions, the linear range of dichlorvos was 5.0 × 10−11–1.0 × 10−7 M. Owing to the high sensitivity and green fluorescent material with high quantum yield, this FRET sensing system was adaptable for automated analyzers using in the rapid determination of a great quantity of samples.
Co-reporter:Bing Sun, Jing Dong, Wei-Jie Shi, Shi-Yun Ai
Sensors and Actuators B: Chemical 2016 Volume 229() pp:75-81
Publication Date(Web):28 June 2016
DOI:10.1016/j.snb.2016.01.063
•Photoactive W-Bi2S3 composites were synthesized in aqueous system without organic additives.•The photoelectrode was fabricated onto ITO based on W-Bi2S3/PTBA heterojunction.•PTBA rendered PEC sensor with enhanced photocurrent and biologically recognition sites.•The proposed PEC sensor depicted high sensitivity and reproducibility for ALVs-J assayA novel photoelectrochemical (PEC) analyzing platform was fabricated based on tungsten-doped Bi2S3 (W-Bi2S3) composite and electropolymerized poly(thiophenyl-3-boronic acid) (PTBA) for detecting subgroup J of avian leukosis virus (ALVs-J). W-Bi2S3 composite was synthesized using a facile hydrothermal method without any organic reagents. Benefiting from the appropriate energy level cascade between PTBA and W-Bi2S3, the PTBA/W-Bi2S3/ITO electrode exhibited improved PEC performance. Based on the reaction between boric acid and sialic acid on the surface of target virus, boronic acids were used as probing receptors for capturing ALVs-J. Alkaline phosphatase assembled on the modified electrode surface was used to catalyze the hydrolysis of ascorbic acid 2-phosphate in situ producing ascorbic acid for electron donating. The proposed PEC sensor for ALVs-J assay showed a wide linear range, high sensitivity and lower detection limit. This method provides a rapid, effective and reusable platform for screening the ALVs-J-infected poultry.A reusable and effective signal-on photoelectrochemical sensing platform for ALVs-J discrimination is constructed based an enhanced photoelectrode with the hierarchical charge transport cascade, by successively organizing W-doped Bi2S3 nanostructures and electropolymerized poly(thiophenyl-3-boronic acid).
Co-reporter:Fengmin Qiao, Qingqing Qi, Zhenzhen Wang, Ke Xu, Shiyun Ai
Sensors and Actuators B: Chemical 2016 Volume 229() pp:379-386
Publication Date(Web):28 June 2016
DOI:10.1016/j.snb.2015.12.109
Manganese selenide (MnSe) nanoparticles as nanocatalysts may present enhanced peroxidase-like catalysis if loaded on conductive graphite carbon nitride (g-C3N4) supports. In this work, MnSe nanoparticles were successfully loaded on the surface of polymeric g-C3N4 as a cocatalyst through a thermal condensation method by calcinating the mixture of pure MnSe, dicyandiamide and cyanuric acid. The morphology and composition of thus-prepared MnSe loaded doped graphite phase carbon nitride nanosheets (MnSe-g-C3N4) were characterized by transmission electron microscopy (TEM), high resolution TEM, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra and X-ray photoelectron spectroscopy (XPS). Structural analyses revealed that the MnSe-g-C3N4 nanoparticles are composed of ultrathin nanosheets with 20 nm lateral diameter. Compared with original MnSe and g-C3N4, the prepared MnSe-g-C3N4 nanosheets could achieve higher aqueous stability and, especially, much stronger peroxidase-like catalysis, presumably resulting from the synergetic effects of conductive carbon nitride and lamellate MnSe nanocatalysts effectively loaded. Significantly, MnSe-g-C3N4 nanosheets were proved to be novel peroxidase mimetics which could quickly catalyze oxidation of the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2, producing a blue colored solution. Kinetic analysis indicates that the catalytic behavior satisfy typical Michaelis–Menten kinetics and follows a ping-pong mechanism. Colorimetric detections of H2O2 and glucose using the MnSe-g-C3N4 nanosheets were conducted with high detection sensitivities, demonstrating the feasibility of practical sensing applications. It is therefore believed that our findings in this study could open up the possibility of utilizing MnSe-g-C3N4 nanosheets as enzymatic mimics in diagnostics and biotechnology fields.
Co-reporter:Xuemei Li, Yan Wang, Jie Luo, Shiyun Ai
Sensors and Actuators B: Chemical 2016 Volume 228() pp:509-514
Publication Date(Web):2 June 2016
DOI:10.1016/j.snb.2016.01.082
In traditional bioanalysis with mesoporous silica nanoparticle (MSN) as carrier, fluorescence quenching by encapsulation of fluorescence molecules in the pores was generally used. In the present work, Au nanoparticle@SiO2 mesoporous silica core–shell nanoparticles (AuNP@SiO2 MSN) was synthesized, and surface plasmon resonance enhanced fluorescence localized on nanopore was observed. In-hole fluorescence enhancement by MSN for detection of adenosine 5′-triphosphate (ATP) was developed, on the base of exonuclease III (Exo III)-assisted cyclic amplification and surface plasmon resonance enhanced fluorescence localized on nanopore. Because of the autocatalytic target recycling amplification and the fluorescence enhancement, this designed protocol provided an ultrasensitive detection of ATP down to 0.1 nM level, and can be utilized into cell lysates analysis.
Co-reporter:Zhiqing Yang, Yanhua Shi, Wenrong Liao, Huanshun Yin, Shiyun Ai
Sensors and Actuators B: Chemical 2016 Volume 223() pp:621-625
Publication Date(Web):February 2016
DOI:10.1016/j.snb.2015.09.159
•A novel photoelectrochemical biosensor was developed for detection of 5-hydroxymethylcytosine.•The biosensor was based on in situ electron donor producing strategy.•The biosensor exhibited high sensitivity and excellent selectivity for 5-hydroxymethylcytosine.•The biosensor uses all wavelengths of light irradiation to increase the utilization rate of light.In this paper, a novel signal-on photoelectrochemical (PEC) biosensor was papered for detecting 5-hydroxymethylcytosine (5-hmC) based on in situ electron donor producing strategy and all wavelengths of light irradiation. Firstly, the amino modified double DNA strand containing 5-hmC was captured on the carboxyl functionalized magnetic bead surface via amide linkage. After treatment with cysteamine in the presence of M.HhaI, the dsDNA with 5-hmC could transformed to amino-derivatized DNA. Subsequently, NHS-biotin could be labeled on the amino-derivative dsDNA and further reacted with avidin conjugated alkaline phosphatase (avidin-ALP). Under the catalysis effect of ALP toward ascorbic acid 2-phosphatetrisodium salt (AAP), ascorbic acid (AA) was in situ produced as electron donor. After magnetic separation, the biosensor can achieved all wavelengths of light irritation and a strong PEC response was obtained using a CdS/ITO as working electrode. The prepared biosensor showed high detection sensitivity with low detection limit of 0.167 nM for 5-hmC.
Co-reporter:Qingyang Li, Dandi Zhou, Pilan Zhang, Ping Man, Zhengbin Tian, Yan Li, Shiyun Ai
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2016 Volume 501() pp:132-137
Publication Date(Web):20 July 2016
DOI:10.1016/j.colsurfa.2016.04.054
•The BiOBr/RC has been prepared via in-situ synthesis method.•The influence of the porous cellulose film to the BiOBr photodegradation of phenol was investigated.•The BiOBr/RC exhibited good photocatalytic activity for the photodegradation of phenol.•The BiOBr/RC is a portable catalyst.A portable catalyst, BiOBr/regenerated cellulose composite films (BiOBr/RC), was prepared for the application of photocatalytic irradiation under visible light. It exhibited good photocatalytic activity for the photodegradation of phenol which means it has potential for the application in photodegradation of organic pollutant. Cellulosic biomass is a kind of green material, and the composite film is easy to recycle and has good reproducibility. So it's a “green” processing for the catalyst can be removed easily from pollution solution after being used and to be used for the next run.
Co-reporter:Nan Wang, Jianchao Sun, Hai Fan, Shiyun Ai
Talanta 2016 Volume 148() pp:301-307
Publication Date(Web):1 February 2016
DOI:10.1016/j.talanta.2015.11.007
•LDHs modified filter paper for detection of heavy metal ions has been developed.•Fe(CN)64- or S2- were successfully intercalated into LDHs modified test strips.•The test strips can detect heavy mental ions by observing the color change.•The test strips were highly stable and reproducible.In this work, a novel approach for facile and rapid detection of heavy metal ions using anion-intercalated layered double hydroxides (LDHs) modified test strips is demonstrated. By intercalating Fe(CN)64− or S2− anions into the interlayers of LDHs on the filter paper, various heavy metal ions can be easily detected based on the color change before and after reaction between the anions and the heavy metal ions. Upon the dropping of heavy metal ions solutions to the test strips, the colors of the test strips changed instantly, which can be easily observed by naked eyes. With the decrease of the concentration, the color depth changed obviously. The lowest detection concentration can be up to 1×10−6 mol L−1. Due to the easily intercalation of anions into the interlayer of the LDHs on test trips, this procedure provides a general method for the construction of LDHs modified test strips for detection of heavy metal ions. The stability of the prepared test strips is investigated. Furthermore, all the results were highly reproducible. The test strips may have potential applications in environmental monitoring fields.
Co-reporter:Yunlei Zhou;Mo Wang;Zhiqing Yang;Linan Lu
Journal of Solid State Electrochemistry 2016 Volume 20( Issue 2) pp:413-419
Publication Date(Web):2016 February
DOI:10.1007/s10008-015-3005-6
Nuclease S1 can catalyze the nonspecific endo- and exonucleolytic cleavage of single-stranded DNA and RNA to yield nucleoside 5′-phosphates and 5′-phosphooligonucleotides. However, it cannot hydrolyze double-stranded DNA, double-stranded RNA, or DNA-RNA hybrid. Inspired by this specific property, a simple electrochemical method was developed for microRNA detection based on hybridization protection against nuclease S1 digestion. In the absence of hybridization process, the assembled probe DNA on the electrode surface can be easily digested by nuclease S1 and a strong electrochemical signal can be generated due to the decreased repulsive force towards the redox probe. However, after hybridization with target microRNA, the digestion activity of nuclease S1 is inhibited, which can lead to a weak electrochemical signal. Based on the change of the electrochemical signal, the detection of target microRNA-319a can be achieved. Under optimal experiment conditions, the electrochemical signal was proportional to microRNA-319a concentration from 1000 to 5 pM and the detection limit was 1.8 pM (S/N = 3). The developed method also showed high detection selectivity and reproducibility. Furthermore, the proposed method was successfully applied to assay the expression level of microRNA-319a in the leaves of rice seedlings after being incubated with different concentrations of 6-benzylaminopurine.
Co-reporter:Bingchen Li, Fei Liu, Yuanyuan Peng, Yunlei Zhou, Wenxuan Fan, Huanshun Yin, Shiyun Ai, Xiansheng Zhang
Biosensors and Bioelectronics 2016 Volume 79() pp:307-312
Publication Date(Web):15 May 2016
DOI:10.1016/j.bios.2015.12.051
•An electrochemical strategy is developed for detecting microRNA-21 in the blood serum of breast cancer patients.•The specificities of T7 Exonuclease and T4 RNA ligase 2 are utilized to improve detection specificity and sensitivity.•The cyclic enzymatic amplification method is used to improve the sensitivity of this biosensor.•The proposed method showed wide linear range and low detection limit.MicroRNA (miRNA) is riveting nowadays due to its close relevance to human malignancies. Exploiting a fast and convenient biosensor for sensitive and specific detecting miRNA is necessary and it has significant meaning for oncology. In this work, to understand the relationship between miRNA-21 and gastric cancer, we employ T4 RNA ligase 2 to initiate specific ligation reaction depending on the sequence of target RNA, and T7 exonuclease to catalyze the first stage cyclic enzymatic amplification method (CEAM) specifically, which also resting on the target RNA sequence, and the second stage CEAM to further amplify the response resulting from the initial target RNA. Our two-stage CEAM strategy can detect miRNA-21 as low as 0.36 fM with remarkable specificity, and most importantly, it can be used to inspect the expression level of miRNA-21 in blood serum of gastric cancer patients. This will offer new perspective for figuring out the pathways of miRNA-21 involving in cancer.
Co-reporter:Nan Wang, Bingchen Li, Fengmin Qiao, Jianchao Sun, Hai Fan and Shiyun Ai
Journal of Materials Chemistry A 2015 vol. 3(Issue 39) pp:7718-7723
Publication Date(Web):25 Aug 2015
DOI:10.1039/C5TB00684H
In this report, stable copper nanoparticles (Cu NPs) were prepared through a facile annealing process using humic acid as the reducing and stabilizing agents. The products were characterized by X-ray powder diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The prepared Cu NPs show remarkably intrinsic peroxidase-like activity, which can rapidly catalyze the oxidation of the peroxidase substrate, 3,3′,5,5′-tetramethylbenzidine (TMB), in the presence of H2O2 to produce a blue-color reaction. The detection limit of H2O2 by Cu NPs can be as low as 1.32 × 10−7 M. More importantly, the prepared Cu NPs show excellent stability, which can hardly be oxidized even after 6 months. Based on the aforementioned mechanism, a simple, rapid and selective colorimetric method for glucose detection was developed, and the detection limit of glucose was 6.86 × 10−7 M. This study provides a novel method for the preparation of stable Cu NPs, which may have widespread applications in the detection of glucose in the human body and pear juice.
Co-reporter:Zhiqing Yang, Wenjing Jiang, Fei Liu, Yunlei Zhou, Huanshun Yin and Shiyun Ai
Chemical Communications 2015 vol. 51(Issue 78) pp:14671-14673
Publication Date(Web):12 Aug 2015
DOI:10.1039/C5CC05921F
A novel electrochemical immunosensor was fabricated for the quantitative detection of 5-hydroxymethylcytosine (5-hmC) in genomic DNA based on anti-5-hmC antibody, biotin functionalized phos-tag and avidin functionalized alkaline phosphatase. It is demonstrated that the levels of 5-hmC are dramatically reduced in human breast cancer tissue compared with those in normal tissue.
Co-reporter:Jing Dong, Juying Hou, Jianxia Jiang, Shiyun Ai
Analytica Chimica Acta 2015 Volume 885() pp:92-97
Publication Date(Web):23 July 2015
DOI:10.1016/j.aca.2015.05.033
•Novel approach for electrochemical detection of non-electroactive OPs was proposed.•PAM was used as electroactive probe for the first time.•The detection system displayed high sensitivity and promptness.•The developed sensor was used in real samples with satisfactory results.An innovative approach for sensitive and simple electrochemical detection of non-electroactive organophosphorus pesticides (OPs) was described in this report. The novel strategy emphasized the fabrication of an oxime-based sensor via attaching pralidoxime (PAM) on graphene quantum dots (GQDs) modified glassy carbon electrode. The introduction of GQDs significantly increased the effective electrode area, and then enlarged the immobilization quantity of PAM. Thus, the oxidation current of PAM was obviously increased. Relying on the nucleophilic substitution reaction between oxime and OPs, fenthion was detected using PAM as the electroactive probe. Under optimum conditions, the difference of oxidation current of PAM was proportional to fenthion concentration over the range from 1.0 × 10−11 M to 5.0 × 10−7 M with a detection limit of 6.8 × 10−12 M (S/N = 3). Moreover, the favorable detection performance in water and soil samples heralded the promising applications in on-site OPs detection.
Co-reporter:Mo Wang, Bingchen Li, Qing Zhou, Huanshun Yin, Yunlei Zhou, Shiyun Ai
Electrochimica Acta 2015 Volume 165() pp:130-135
Publication Date(Web):20 May 2015
DOI:10.1016/j.electacta.2015.03.011
•Signal “on” and electrochemical immunosensing biosensor was fabricated.•MicroRNA was detected using this biosensor.•S9.6 antibody has high specificity and affinity to DNA:RNA hybrids.•ALP-IgG was used as enzymatic signal amplification.•The method holds a great promise for further investigation the role of microRNAs in phytohormone signaling transduction.In this work, we proposed a selective and sensitive biosensor for microRNA detection based on the high specificity and affinity of anti-DNA:RNA hybrids antibody (S9.6 antibody) and alkaline phosphatase catalytic signal amplification. Briefly, after the hybridization of probe DNA and the target microRNA, the S9.6 antibody can be captured on the electrode surface through antigen-antibody immunoreaction. Then, alkaline phosphatase labeled goat anti-mouse IgG (ALP-IgG) was further captured on the electrode surface through the specific recognition effect between the primary antibody and the secondary antibody. Finally, ALP catalyzed the hydrolysis reaction of p-nitrophenyl phosphate to generate p-nitrophenol, resulting in a electrochemical oxidation signal. The simple signal amplification assay performed a successful linear range from 0.5-500 fM with a detection limit of 0.40 fM. Moreover, this biosensor exhibited high selectivity with discriminating only single-base mismatched microRNA sequence. Additionally, the simplicity of this method hold a great promise for further investigation of the role of microRNAs in phytohormone signaling transduction.
Co-reporter:Pei Liu, Junling Pang, Huanshun Yin, Shiyun Ai
Analytica Chimica Acta 2015 Volume 879() pp:34-40
Publication Date(Web):16 June 2015
DOI:10.1016/j.aca.2015.04.023
•A nano mesoporous silica-based biosensor was fabricated.•DNA methylation was detected using this biosensor.•G-quadruplex was used as a lock for methylene blue releasing.•Zebularine was used for the investigation of inhibitor on the activity of M. SssI MTase.The abnormal level of DNA methyltransferase (MTase) may cause the aberrant DNA methylation, which has been found being associated with a growing number of human diseases, so it is necessary to create a sensitive and selective method to detect DNA MTase activity. In this paper, a new type of DNA functionalized nano mesoporous silica (MSNs) was creatively introduced to the detection of DNA MTase activity with G-quadruplex as a lock for signal molecule to release. The method was carried out by designing a particular DNA which could fold into G-quadruplex and complement with probe DNA. Next, MSNs was prepared before blocking methylene blue (MB) by G-quadruplex. Probe DNA was then fixed on gold nanoparticles modified glass carbon electrode, and the material was able to be transferred to the surface of electrode by DNA hybridization. After methylation of DNA MTase and the cutting of restriction endonuclease, the electrode was transferred to phosphate buffer solution (pH 9.0) for the releasing of MB. The response of differential pulse voltammetry was obtained from the release of MB. Consequently, the difference of signals with or without methylation could prove the assay of M. SssI MTase activity. The results showed that the responses from MB increased linearly with the increasing of the M. SssI MTase concentrations from 0.28 to 50 U mL−1. The limit of detection was 0.28 U mL−1. In addition, Zebularine, a nucleoside analog of cytidine, was utilized for studying the inhibition activity of M. SssI MTase.
Co-reporter:Fengmin Qiao, Zhenzhen Wang, Ke Xu and Shiyun Ai
Analyst 2015 vol. 140(Issue 19) pp:6684-6691
Publication Date(Web):18 Aug 2015
DOI:10.1039/C5AN01268F
A facile process was developed for the synthesis of FeSe–Pt@SiO2 nanospheres based on the hydrothermal treatment of FeCl3·6H2O, selenium and NaBH4 in ethanolamine solvent, followed by reducing HPtCl4 with NaBH4 in the presence of FeSe particles to obtain FeSe coated with Pt NPs (FeSe–Pt), ending with a surfactant assembled sol–gel process to obtain FeSe–Pt@SiO2. The morphology and composition of FeSe–Pt@SiO2 were characterized by transmission electron microscopy, high resolution TEM, X-ray diffraction and Fourier transform infrared spectroscopy. Structural analyses revealed that FeSe–Pt@SiO2 nanospheres were of regular spherical shape with smooth surfaces due to the SiO2 shells, compared with FeSe particles with 150 nm lateral diameter. The prepared FeSe–Pt@SiO2 nanospheres possessed both intrinsic glucose oxidase (GOx-) and peroxidase-mimic activities, and we engineered an artificial enzymatic cascade system with high activity and stability based on this nanostructure. The good catalytic performance of the composites could be attributed to the synergy between the functions of FeSe particles and Pt NPs. Significantly, the FeSe–Pt@SiO2 nanospheres as robust nanoreactors can catalyze a self-organized cascade reaction, which includes oxidation of glucose by oxygen to yield gluconic acid and H2O2, and then oxidation of 3,3,5,5-tetramethylbenzidine (TMB) by H2O2 to produce a colour change. Colorimetric detection of H2O2 and glucose using the FeSe–Pt@SiO2 nanospheres was conducted with high detection sensitivities, 0.227 nM and 1.136 nM, respectively, demonstrating the feasibility of practical sensing applications. It is therefore believed that our findings in this study could open up the possibility of utilizing FeSe–Pt@SiO2 nanospheres as enzymatic mimics in diagnostic and biotechnology fields.
Co-reporter:Nan Wang, Zhenwei Han, Hai Fan and Shiyun Ai
RSC Advances 2015 vol. 5(Issue 111) pp:91302-91307
Publication Date(Web):20 Oct 2015
DOI:10.1039/C5RA18957H
In this study, copper nanoparticles modified graphitic carbon nitride nanosheets (Cu NPs/g-C3N4) as a novel peroxidase mimetic were successfully prepared by the calcination of dicyandiamide–Cu2+ complex with the assistance of humic acid. The morphology and structure of the product were characterized by X-ray powder diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The prepared Cu NPs/g-C3N4 was found to have highly peroxidase-like activity, which can rapidly catalyze the oxidation of peroxidase substance 3,3′,5,5′-tetramethylbenzidine (TMB) to produce a blue color in the presence of H2O2. Accordingly, a simple, selective and fast colorimetric method was developed for H2O2 and glucose detection. The prepared Cu NPs/g-C3N4 exhibited low detection limits of 3.2 × 10−8 M and 3.7 × 10−7 M for H2O2 and glucose, respectively, due to the excellent peroxidase-like activity of Cu NPs/g-C3N4 originating from the synergistic effect of Cu NPs and g-C3N4. In this work, we utilized the easily forming complex ability of dicyandiamide and Cu2+ ions to form a homogeneous precursor solution, and then obtained the CuNPs/g-C3N4 product; such a method may have wide applications in novel composite nanomaterial preparation. The product may have promising applications in medical diagnostics and biotechnology fields.
Co-reporter:Zhengbin Tian;Lei Zong;Rujie Niu;Xiao Wang;Yan Li;Shiyun Ai
Journal of Applied Polymer Science 2015 Volume 132( Issue 25) pp:
Publication Date(Web):
DOI:10.1002/app.42057
ABSTRACT
Conversion of lignin derived from lignocellulosic biomass to bio-oil has the promising potential to significantly reduce petroleum dependence. For that purpose, it is necessary to search for a low-cost lignin source. In this study, lignin sample was separated from straw pulping black liquor by HCl-precipitation, followed by extraction with a mixture of dioxane and water. The content of lignin in the total black liquor solid reached up to 34.8%, determined by UV spectroscopy, and the yield could account for 74.4% of the total lignin composition. The structure of lignin was investigated by various spectroscopic techniques such as FTIR, 1H-NMR, XRD, and XPS. The structural analysis revealed that recovered lignin preserved basic lignin structure, but had relatively lower amount of β-O-4 linkages. The molecular weights were studied through THF-eluted GPC showing that separated lignin had the low Mn, which was favorable for the full degradation process during conversion of lignin to bio-oil. Therefore, a feasible solution for effective utilization of lignin in straw pulping black liquor as feedstock for bio-oil was proposed in the study. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42057.
Co-reporter:Nan Wang;Jianchao Sun;Lijian Chen;Hai Fan;Shiyun Ai
Microchimica Acta 2015 Volume 182( Issue 9-10) pp:1733-1738
Publication Date(Web):2015 July
DOI:10.1007/s00604-015-1506-8
A nanomaterial of the chemical composition Cu2(OH)3Cl-CeO2 and with a large surface area is shown to be a viable peroxidase mimetic. It was synthesized by co-precipitation of an aqueous solution containing Ce(III) chloride, Cu(II) chloride and hexamethylenetetramine by adding an ionic liquid. The material was characterized by scanning electron microscopy and X-ray powder diffractometry. The composite possesses peroxidase-like activity and catalyzes the oxidation of the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine by H2O2 to produce a blue product. Based on this finding, a simple, rapid and selective colorimetric method was worked out for the determination of glucose and cholesterol by using the respective oxidases and by quantifying the H2O2 formed. Both glucose and cholesterol can be determined by this method at levels as low as 50 µM.
Co-reporter:Bingchen Li;Xue Li;Mo Wang;Zhiqing Yang
Journal of Solid State Electrochemistry 2015 Volume 19( Issue 5) pp:1301-1309
Publication Date(Web):2015 May
DOI:10.1007/s10008-015-2747-5
A selective and sensitive photoelectrochemical assay was proposed for microRNA detection based on the isothermal cycle hybridization amplification of microRNA-21 that originated from the specific cleavage activity of duplex-specific nuclease (DSN) toward a DNA probe in DNA-RNA double helix and in situ enzymatic production of electron donor of ascorbic acid. After the biotin-functionalized DNA probe hybridized with complementary target microRNA-21, the hybridized DNA probe could be cleaved by DSN and microRNA-21 was released back to the incubation solution. The released microRNA could be further hybridized with the remaining single-strand DNA probe; thus, the isothermal cycle hybridization amplification would be formed. As a result, little avidin-alkaline phosphatase conjugate could be captured due to the release of biotin originating from the DSN cleavage. The distinct photocurrent change between a control biosensor and the DSN cleavage biosensor achieved label-free microRNA-21 detection with the linear range from 1 to 500 fM. The fabricated biosensor showed high detection selectivity even for one-base mismatched sequence. The attempt was carried out to directly assay the expression level change of microRNA-21 in total RNA extracted from chicken fibroblast cells infected with subgroup J avian leukosis virus.
Co-reporter:Juying Hou, Jing Dong, Haishuang Zhu, Xue Teng, Shiyun Ai, Minglin Mang
Biosensors and Bioelectronics 2015 Volume 68() pp:20-26
Publication Date(Web):15 June 2015
DOI:10.1016/j.bios.2014.12.037
•A novel methyl parathion sensor was developed using carbon dots.•The carbon dots were prepared by a simple hydrothermal reaction.•The sensor was based on the fluorescence quenching of carbon dots.•The quenching is owing to the formation of quinone on the surface of carbon dots.•The sensor shows a low detection limit, wide linear range, and good reproducibility.In this paper, a simple and sensitive fluorescent sensor for methyl parathion is developed based on l-tyrosine methyl ester functionalized carbon dots (Tyr-CDs) and tyrosinase system. The carbon dots are obtained by simple hydrothermal reaction using citric acid as carbon resource and l-tyrosine methyl ester as modification reagent. The carbon dots are characterized by transmission electron microscope, high resolution transmission electron microscopy, X-ray diffraction spectrum, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The carbon dots show strong and stable photoluminescence with a quantum yield of 3.8%. Tyrosinase can catalyze the oxidation of tyrosine methyl ester on the surface of carbon dots to corresponding quinone products, which can quench the fluorescence of carbon dots. When organophosphorus pesticides (OPs) are introduced in system, they can decrease the enzyme activity, thus decrease the fluorescence quenching rate. Methyl parathion, as a model of OPs, was detected. Experimental results show that the enzyme inhibition rate is proportional to the logarithm of the methyl parathion concentration in the range 1.0×10−10–1.0×10−4 M with the detection limit (S/N=3) of 4.8×10−11 M. This determination method shows a low detection limit, wide linear range, good selectivity and high reproducibility. This sensing system has been successfully used for the analysis of cabbage, milk and fruit juice samples.
Co-reporter:Huanshun Yin, Xinxu Wang, Yunlong Guo, Yunlei Zhou, Shiyun Ai
Biosensors and Bioelectronics 2015 Volume 66() pp:77-83
Publication Date(Web):15 April 2015
DOI:10.1016/j.bios.2014.11.014
•A novel electrochemical biosensor is fabricated for kinase activity assay.•Carboxypeptidase Y digestion of peptide is inhibited due to phosphorylation.•This method shows high sensitivity with detection limit of 0.047 unit/mL.•The developed method can also be applied to screen inhibitors.An effective assay method for monitoring protein kinase activity and screening inhibitors is greatly beneficial to kinase-related drug discovery, early diagnosis of diseases, and therapeutic effect evaluation. Herein, we develop a simple electrochemical method for detecting the activity of casein kinase II (CK2) based on phosphorylation against carboxypeptidase Y (CPY) digestion triggered signal amplification, where CK2 catalyzed phosphorylation event protects the substrate peptide from the digestion of CPY, maintains the repulsive force of the substrate peptide towards the redox probe, and results in a weak electrochemical signal. Whereas, without phosphorylation, the substrate peptide is digested by CPY and a strong electrochemical signal is obtained. The detection feasibility is demonstrated for the assay of CK2 activity with low detection limit of 0.047 unit/mL. Moreover, the biosensor was used for the analysis of kinase inhibition. Based on the electrochemical signal dependent inhibitor concentration, the IC50 value of ellagic acid was estimated to be 39.77 nM. The proposed method is also successfully applied to analyze CK2 activity in cell lysates, proving the applicability in complex biological samples.
Co-reporter:Zhiqing Yang, Fengrui Wang, Mo Wang, Huanshun Yin, Shiyun Ai
Biosensors and Bioelectronics 2015 Volume 66() pp:109-114
Publication Date(Web):15 April 2015
DOI:10.1016/j.bios.2014.11.015
•A novel signal-on photoelectrochemical immunosensor was fabricated.•M. SssI methyltransferase activity and inhibitor was detected using this immunosensor.•Anti-5-methylcytosine antibody was used to recognize methylated DNA.•In situ enzymatic ascorbic acid production as electron donor.•Immunogold labeled streptavidin amplification units were adopted to obtain high sensitivity.In this work, a novel signal-on photoelectrochemical (PEC) immunosensor was fabricated for M.SssI methyltransfease (MTase) activity analysis and inhibitor screening based on an in situ electron donor producing strategy, where the anti-5-methylcytosine antibody was selected as DNA CpG methylation recognition unit, gold nanoparticle labeled streptavidin (SA-AuNPs) as signal amplification unit and alkaline phosphatase conjugated biotin (ALP-Biotin) as enzymatic unit. In the presence of M.SssI MTase, hairpin DNA1 containing the palindromic sequences of 5′-CCGG-3′ in its stem was methylated. After hybridization with biotin-conjugated DNA2, the stem-loop structure of the hairpin DNA1 was unfolded and the duplex strand DNA (dsDNA) was formed. Then, the dsDNA was captured on the surface of anti-5-methylcytosine antibody modified electrode through the specific immuno-reaction. Afterwards, SA-AuNPs and ALP-Biotin was further captured on the electrode surface through the specific reaction between biotin and streptavidin. Under the catalysis effect of ALP towards ascorbic acid 2-phosphate trisodium salt (AAP), ascorbic acid (AA) was in situ produced as electron donor and a strong PEC response was obtained. The fabricated biosensor showed high detection sensitivity with low detection limit of 0.33 unit/mL for M.SssI MTase. Furthermore, the inhibition research suggested that RG108 could inhibit the M.SssI MTase activity with the IC50 value of 152.54 nM.
Co-reporter:Huanshun Yin, Bing Sun, Linfeng Dong, Bingchen Li, Yunlei Zhou, Shiyun Ai
Biosensors and Bioelectronics 2015 Volume 64() pp:462-468
Publication Date(Web):15 February 2015
DOI:10.1016/j.bios.2014.09.070
•A signal “on” photoelectrochemical biosensor was fabricated for protein kinase activity assay.•g-C3N4 was used as the photoelectric conversion material with visible-light activity.•Phosphate group can be specific identified by Phos-tag.•The developed method can be applied to detect kinase in cell lysates.A highly sensitive and selective photoelectrochemical (PEC) biosensor is fabricated for the detection of protein kinase activity based on visible-light active graphite-like carbon nitride (g-C3N4) and the specific recognition utility of Phos-tag for protein kinase A (PKA)-induced phosphopeptides. For assembling the substrate peptides, g-C3N4 and gold nanoparticles (g-C3N4-AuNPs) complex is synthesized and characterized. When the immobilized peptides on g-C3N4–AuNPs modified ITO electrode are phosphorylated under PKA catalysis, they can be specifically identified and binded with biotin functionalized Phos-tag (Phos-tag–biotin) in the presence of Zn2+. Then, through the specific interaction between biotin and avidin, avidin functionalized alkaline phosphatase (avidin-ALP) is further assembled to catalyze its substrate of l-ascorbic acid-2-phosphate trisodium salt (AAP) to produce electron donor of ascorbic acid (AA), resulting an increased photocurrent compared with the absence of phosphorylation event. Based on the specific identification effect of Phos-tag, the fabricated biosensor presents excellent selectivity for capturing the phosphorylated serine residues in the substrate peptides. With the good photoactivity of g-C3N4 and ALP-catalyzed signal amplification, the fabricated biosensor presents high sensitivity and low detection limit (0.015 unit/mL, S/N=3) for PKA. The applicability of this PEC biosensor is further testified by the evaluation of PKA inhibition by HA-1077 with the IC50 value of 1.18 μM. This new strategy is also successfully applied to detect the change of PKA activity in cancer cell lysate with and without drug stimulation. Therefore, the developed PEC method has great potential in screening of kinase inhibitors and highly sensitive detection of kinase activity.
Co-reporter:Huanshun Yin, Mo Wang, Bingchen Li, Zhiqing Yang, Yunlei Zhou, Shiyun Ai
Biosensors and Bioelectronics 2015 Volume 63() pp:26-32
Publication Date(Web):15 January 2015
DOI:10.1016/j.bios.2014.07.016
•A sensitive electrochemical method is developed for kinase activity assay.•Phos-tag-biotin is used as recognition element for phosphate group.•Enzymatic signal amplification was employed to improve the sensitivity.•Inhibitor effect of ellagic acid and H-89 is performed with satisfactory results.•This method is applied to detect kinase activity in cell lysates.A simple, highly sensitive and selective electrochemical assay is developed for the detection of protein kinase A (PKA) activity based on the specific recognition utility of Phos-tag for kinase-induced phosphopeptides and enzymatic signal amplification. When the substrate peptide was phosphorylated by PKA reaction, they could specifically bind with Phos-tag-biotin in the presence of Zn2+ through the formation of a specific noncovalent complex with the phosphomonoester dianion in phosphorylated peptides. Through the further specific interaction between biotin and avidin, avidin functionalized horseradish peroxidase (HRP) can be captured on the electrode surface. Under the catalytic effect of HRP, a sensitive electrochemical signal for benzoquinone was obtained, which was related to PKA activity. Under the optimal experiment conditions, the proposed electrochemical method presented dynamic range from 0.5 to 25 unit/mL with low detection limit of 0.15 unit/mL. This new detection strategy was also successfully applied to analyze the inhibition effect of inhibitors (ellagic acid and H-89) on PKA activity and monitored the PKA activity in cell lysates. Therefore, this Phos-tag-based electrochemical assay offers an alternative platform for PKA activity assay and inhibitor screening, and thus it might be a valuable tool for development of targeted therapy and clinical diagnosis.
Co-reporter:Huanshun Yin, Yunlei Zhou, Zhiqing Yang, Yunlong Guo, Xinxu Wang, Shiyun Ai, Xiansheng Zhang
Sensors and Actuators B: Chemical 2015 Volume 221() pp:1-6
Publication Date(Web):31 December 2015
DOI:10.1016/j.snb.2015.06.045
•An electrochemical immunosensor was fabricated for RNA methylation detection.•N6-methyladenosine antibody was used as capture probe for RNA methylation.•The developed method showed wide linear range from 0.01 to 10 nM and the detection limit was 2.57 pM.•The immunosensor was applied to detect the methylation level of mRNA in rice seedling leaves.N6-methyladenosine (m6A) is a ubiquitous modification in mRNA and other RNAs across most eukaryotes, which is likely dynamically regulated throughout developmental processes. In this work, an electrochemical immunosensor was fabricated for RNA methylation detection using gold nanoparticles modified glassy carbon electrode (AuNPs/GCE) as substrate electrode. The assembly of 4-aminophenylboronic acid on AuNPs/GCE triggered the further immobilization of anti-m6A antibody on the substrate electrode through the specific interaction between boric acid and glycosyl of antibody, which led to the following capture of methylated RNA through the immunoreaction. A decreased electrochemical reduction signal of the redox probe of [Fe(CN)6]3− was obtained based on the synergistic effect of electrostatic repulsion and steric hindrance. The developed method showed a wide linear range for methylated RNA from 0.01 to 10 nM and the detection limit was 2.57 pM (S/N = 3). Moreover, the down-regulated expression of methylation level of mRNA in the leaves of rice seedlings after incubation with 6-benzylaminopurine was confirmed by the fabricated biosensor, indicating the great potential for assaying the expression level of methylated RNA in real sample.
Co-reporter:Huanshun Yin, Zhiqing Yang, Bingchen Li, Yunlei Zhou, Shiyun Ai
Biosensors and Bioelectronics 2015 Volume 66() pp:266-270
Publication Date(Web):15 April 2015
DOI:10.1016/j.bios.2014.11.026
•An electrochemical method was developed for DNA demethylase detection.•Demethylation triggered BstUI and Exo. III digestion towards dsDNA was achieved.•The low detection limit of 0.15 ng/mL was obtained.•The developed method presented high detection selectivity.Herein, an electrochemical biosensor was fabricated for DNA demethylase detection based on DNA demethylation triggered endonuclease BstUI and Exonuclease III digestion. After the double-strand DNA was demethylated, it can be further digested by BstUI and formed a blunt end at the electrode surface. Then, the remained fragment of DNA–DNA duplex was further cleaved by exonuclease III and led to increased electrochemical signal. Based on this detection strategy, the biosensor showed high sensitivity with low detection limit of 0.15 ng/mL. Moreover, the developed method also presented high selectivity and acceptable reproducibility. This work provides a novel detection platform for DNA demethylase detection.
Co-reporter:Mo Wang, Zhengliang Fu, Bingchen Li, Yunlei Zhou, Huanshun Yin, and Shiyun Ai
Analytical Chemistry 2014 Volume 86(Issue 12) pp:5606
Publication Date(Web):June 4, 2014
DOI:10.1021/ac5010376
Taking advantage of the special exodeoxyribonuclease activity of T7 exonuclease, a simple, sensitive, selective, and label-free microRNA biosensor based on the cyclic enzymatic amplification method (CEAM) has been proposed. First, thiol functionalized DNA probes were assembled onto a gold nanoparticles modified gold electrode surface through a Au–S bond, followed by hybridizing with target miRNA. Subsequently, DNA in RNA/DNA duplexes was digested by T7 exonuclease, which can release the microRNA molecules from the electrode surface and return into the buffer solution. Meanwhile, the released microRNA can further hybridize with the unhybridized DNA probes on the modified electrode surface. On the basis of it, an isothermal amplification cycle is realized. The T7 exonuclease-assisted CEAM achieved a low detection limit of 0.17 fM. Moreover, this assay presents excellent specificity with discriminating only a single-base mismatched microRNA sequence. Furthermore, this work can also be applied to detect avian leukemia based on the decreased expression level of microRNA-21.
Co-reporter:Zhenning Xu, Huanshun Yin, Yunxiang Han, Yunlei Zhou, Shiyun Ai
Analytica Chimica Acta 2014 Volume 829() pp:9-14
Publication Date(Web):4 June 2014
DOI:10.1016/j.aca.2014.04.024
•A new electrochemical protocol was fabricated.•The DNA-based hybridization chain reaction was used for signal amplification.•Fluorouracil and daunorubicin hydrochloride could inhibit the DNA MTase activity.•Bisphenol A and nonyl phenol could improve the DNA MTase activity.In this work, a novel electrochemical protocol with signal amplification for determination of DNA methylation and methyltransferase activity using DNA-based hybridization chain reaction (HCR) was proposed. After the gold electrode was modified with dsDNA, it was treated with M.SssI MTase, HpaII endonuclease, respectively. And then the HCR was initiated by the target DNA and two hairpin helper DNAs, which lead to the formation of extended dsDNA polymers on the electrode surface. The signal was amplified by the labeled biotin on the hairpin probes. As a result, the streptavidin-alkaline phosphatase (S-ALP) conjugated on the electrode surface through the specific interaction between biotin and S-ALP. ALP could convert 1-naphthyl phosphate into 1-naphthol and the latter could be electrochemically oxidized, which was used to monitor the methylation event and MTase activity. The HCR assay presents good electrochemical responses for the determination of M.SssI MTase at a concentration as low as 0.0067 unit mL−1. Moreover, the effects of anti-cancer drug and environmental phenolic hormone on M.SssI MTase activity were also investigated. The results indicated that 5-fluorouracil and daunorubicin hydrochloride could inhibit the activity, and the opposite results were obtained with bisphenol A and nonylphenol. Therefore, this method can not only provide a platform to screen the inhibitors of DNA MTase and develop new anticancer drugs, but also offer a novel technique to investigate the possible carcinogenesis mechanism.
Co-reporter:Fengmin Qiao, Weijie Shi, Jing Dong, Wei Lv and Shiyun Ai
RSC Advances 2014 vol. 4(Issue 84) pp:44614-44620
Publication Date(Web):11 Sep 2014
DOI:10.1039/C4RA08200A
Hemin has been successfully modified onto the surface of CuAl layered double hydroxide nanosheets by a simple coprecipitation process, which afforded a hemin modified CuAl layered double hydroxide (H-LDH) hybrid functional material that exhibited protective effects against the harmful ONOO−. The obtained products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy, which showed that the samples had hexagonal symmetry structure with a mean lateral size of 1 μm, on the surface of which were adsorbed round particles with a diameter of about 300 nm. A detailed inhibition study on ONOO−-mediated nitration reactions indicated that the interaction between hemin and LDHs results in a synergistic effect, which leads to an efficient reduction of ONOO− to nitrate. The present study suggests that the H-LDHs had an efficient ONOO− scavenging ability, and may well be a potent ONOO− scavenger for protection of the cellular defense activity against ONOO− involved diseases.
Co-reporter:Yuqin Li, Minrong Xu, Peipei Li, Jing Dong and Shiyun Ai
Analytical Methods 2014 vol. 6(Issue 7) pp:2157-2162
Publication Date(Web):13 Jan 2014
DOI:10.1039/C3AY41820K
A new nonenzymatic electrochemical sensor was developed for sensitive detection of methyl parathion based on graphene nanosheets (GNs)/gadolinium Prussian Blue analogue (gadolinium hexacyanoferrate, GdHCF) modified glassy carbon electrode. The new sensor combined the individual properties of GNs (high conductivity and adsorption affinity) and GdHCF (high surface area and special catalytic activity), and realized efficient enrichment and electrochemical stripping voltammetric detection of methyl parathion. Under optimum conditions, the reduction current was proportional to methyl parathion concentration over the range from 0.008 to 10 μM with a detection limit of 1 nM. The sensor displayed high sensitivity, acceptable stability and selectivity, and realized reliable quantification of methyl parathion in practical environment samples.
Co-reporter:Yunlei Zhou, Bingchen Li, Mo Wang, Zhiqing Yang, Huanshun Yin, Shiyun Ai
Analytica Chimica Acta 2014 840() pp: 28-32
Publication Date(Web):20 August 2014
DOI:10.1016/j.aca.2014.06.020
•DNA demethylase activity was assayed by electrochemical method.•Double enzyme system of DNA demethylase and BstUI endonuclease was applied.•The detection is based on alkaline phosphatase catalytic signal amplification.•This method showed high detection selectivity and good sensitivity.A novel electrochemical method is developed for detection of DNA demethylation and assay of DNA demethylase activity. This method is constructed by hybridizing the probe with biotin tagged hemi-methylated complementary DNA and further capturing streptavidin tagged alkaline phosphatase (SA-ALP) to catalyze the hydrolysis reaction of p-nitrophenyl phosphate. The hydrolysate of p-nitrophenol (PNP) is then used as electrochemical probe for detecting DNA demethylation and assaying the activity of DNA demethylase. Demethylation of target DNA initiates a degradation reaction of the double-stranded DNA (dsDNA) by restriction endonuclease of BstUI. It makes the failed immobilization of ALP, resulting in a decreased electrochemical oxidation signal of PNP. Through the change of this electrochemical signal, the DNA demethylation is identified and the activity of DNA demethylase is analyzed with low detection limit of 1.3 ng mL−1. This method shows the advantages of simple operation, cheap and miniaturized instrument, high selectivity. Thus, it provides a useful platform for detecting DNA demethylation, analyzing demethylase activity and screening inhibited drug.
Co-reporter:Zhenning Xu, Huanshun Yin, Lingling Huo, Yunlei Zhou, Shiyun Ai
Sensors and Actuators B: Chemical 2014 192() pp: 143-149
Publication Date(Web):
DOI:10.1016/j.snb.2013.10.099
Co-reporter:Fengmin Qiao, Lijian Chen, Xueni Li, Lifang Li, Shiyun Ai
Sensors and Actuators B: Chemical 2014 193() pp: 255-262
Publication Date(Web):
DOI:10.1016/j.snb.2013.11.108
Co-reporter:Jianchao Sun, Yanbing Zhang, Juan Cheng, Hai Fan, Jianying Zhu, Xin Wang, Shiyun Ai
Journal of Molecular Catalysis A: Chemical 2014 Volume 382() pp:146-153
Publication Date(Web):February 2014
DOI:10.1016/j.molcata.2013.11.004
•Novel Ag/AgCl/Zn-Cr LDHs photocatalyst was prepared by an anion-exchange method.•Ag/AgCl particles were uniformly grown on the surface of Zn-Cr LDHs materials.•Ag/AgCl/Zn-Cr LDHs shows the best activity in the photodegradation of RhB.•Holes and O2− are the two main reactive species for RhB degradation.•The photocatalytic mechanism was proposed.A novel composite photocatalyst Ag/AgCl/Zn-Cr layered double hydroxides (LDHs) was prepared by a facile anion-exchange precipitation method. It was found that Ag/AgCl particles were uniformly grown on the surface of Zn-Cr LDHs materials on a large scale, and the composite shows well visible-light absorption ability. The photocatalytic degradation studies on Rhodamine B (RhB) indicate that Ag/AgCl/Zn-Cr LDHs composite shows enhanced visible-light photocatalytic abilities for degradation of organic pollutants than Ag/AgCl and Zn-Cr LDHs. The photocatalytic mechanism was analyzed by active species trapping experiments. It revealed that the h+ and O2− are the two main reactive species for RhB degradation by Ag/AgCl/Zn-Cr LDHs composite, and the proportion of h+ greatly increases compared to that of Ag/AgCl and Zn-Cr LDHs, indicating that an efficient charge separation is crucial for the enhancement of the photocatalytic activities. This work provides an approach to fabricate novel types of visible-light-induced composite photocatalysts for environment treatment.A novel composite photocatalyst Ag/AgCl/Zn-Cr LDHs was prepared by a facile anion-exchange precipitation method, which shows enhanced visible-light photocatalytic abilities for degradation of RhB.
Co-reporter:Xindong Wang, Jing Dong, Xinyu Liu, Yanzhen Liu, Shiyun Ai
Biosensors and Bioelectronics 2014 Volume 54() pp:85-90
Publication Date(Web):15 April 2014
DOI:10.1016/j.bios.2013.10.051
•Avian leukosis virus subgroup J was detected by a sandwich-type electrochemical immunoassay.•The novel pH-controlled immunosensor was based on hollow mesoporous silica and apoferritin combined system.•The goal of this study was to introduce more electroactive probes into the electrochemical immunosensor.•The immunosensor exhibited high sensitivity and wide linear range.A novel pH-controlled immunosensor using hollow mesoporous silica and apoferritin combined system has been reported for the first time. The goal of this study was to introduce more electroactive probes into the electrochemical immunosensor. Under such background, we focused our attention on hollow mesoporous silica and apoferritin, both of which have admirable accommodating performances and can be applied for encapsulating electroactive probes. Based on the pH-controlled disassociation–reconstitution process of apoferritin and the mesoporous channels of silica, after the appropriate chemical modification, apoferritin could be fabricated with silica. The results showed that the hollow mesoporous silica and apoferritin combined system was successfully assembled. The excellent performance of the combined system can be applied for ultrasensitive detection of a target virus.
Co-reporter:Mo Wang;Huanshun Yin;Zhengliang Fu
Journal of Solid State Electrochemistry 2014 Volume 18( Issue 10) pp:2829-2835
Publication Date(Web):2014 October
DOI:10.1007/s10008-014-2531-y
MicroRNAs (miRNAs), a class of small endogenous nonprotein-coding RNAs, regulate a wide range of biological processes, and their abnormal expressions are related to the growth and development of plants. Thus, a simple, rapid, and highly sensitive assay for miRNA detection is of great significance. In this work, a label-free and ultrasensitive assay for miRNA detection using protein cage nanoparticles has been developed. Apoferritin-encapsulated Cu nanoparticles (Cu-apoferritin) could be immobilized on the electrode through special reaction between amino and carboxyl. Hybridization event between the probe DNA and the target miRNA-159a is confirmed by electrochemical oxidation signal after Cu released into the detection buffer by adjusting the pH. This assay is highly selective and sensitive with a low detection limit of 3.5 fM. Moreover, the developed method can even discriminate single-base mismatched strand between the complementary targets. The effect of abscisic acid on the expression level of miRNA-159a in Arabidopsis thaliana seeds was also investigated.
Co-reporter:Huanshun Yin, Mo Wang, Yunlei Zhou, Xiaoyan Zhang, Bing Sun, Guihua Wang, Shiyun Ai
Biosensors and Bioelectronics 2014 Volume 53() pp:175-181
Publication Date(Web):15 March 2014
DOI:10.1016/j.bios.2013.09.053
•A signal-on photoelectrochemical biosensor was fabricated for microRNA detection.•Bi2S3 were used as photoactive material and ascorbic acid used as electron donor.•Ascorbic acid was released from biotin functionalized AA loaded apoferritin.•The developed method could directly detect microRNA-21 in extracted total RNA.A novel signal “on” type of photoelectrochemical biosensor for microRNA-21 hybridization detection was fabricated, where Bi2S3 nanorods were used as photoactive material with a maximum adsorption at 450 nm visible light, hairpin-structure DNA as detecting probe, streptavidin as signal capturing unit and biotin functionalized ascorbic acid loaded apoferritin as signal amplification unit. Hybridization between the probe and the target microRNA-21 was confirmed by the increased photocurrent of the biosensor after electron donor of ascorbic acid was introduced into the detection buffer by digesting the apoferritin by trypsase, indicating that this method could be used fProd. Type: FTPor quantitative measurements, and the discrimination of the complementary from mismatched microRNA-21. Under the optimal detection conditions, the photoelectrochemical biosensor displayed a linear range of 1–5000 fM and a low detection limit of 0.35 fM for microRNA-21 determination. Moreover, the down-regulated expression of microRNA-21 in poultry cells and tissues infecting with avian leukosis viruses was confirmed by directly detecting microRNA-21 in extracted total RNA. This proposed strategy may open a new avenue for the applications of photoelectrochemical biosensor for oligonucleotides detection using visible light irradiation, which could largely reduce the destructive effect of UV light on biomolecules.
Co-reporter:Mo Wang, Huanshun Yin, Nannan Shen, Zhenning Xu, Bing Sun, Shiyun Ai
Biosensors and Bioelectronics 2014 Volume 53() pp:232-237
Publication Date(Web):15 March 2014
DOI:10.1016/j.bios.2013.09.069
•Signal "on" and visible light photoelectrochemical biosensor was fabricated.•MicroRNA was detected using this biosensor.•Bi2S3 showed high photoactivity and generated strong photocurrent.•In situ generation of ascorbic acid catalytic by enzyme was used as electron donor.•The expression of microRNA-21 in chicken cells infected with ALVs decreased.In this work, a photoelectrochemical (PEC) biosensor was fabricated for sensitive and specific detection of microRNA based on Bi2S3 nanorods and enzymatic signal amplification. Using the catalytic effect of alkaline phosphatase on l-ascorbic acid 2-phosphate trisodium salt (AAP), ascorbic acid (AA) was in situ generated and used as electron donor. Based on this, a signal-on protocol was successively achieved for microRNAs detection due to the dependence of photocurrent response on the concentration of electron donor of AA. The results demonstrated that the photocurrent response enhanced with increasing the hybridized concentration of microRNA. Under the amplification of the immunogold labeled streptavidin (SA-AuNPs), a low detection limit of 1.67 fM was obtained. The fabricated biosensor showed good detection stability and specificity, and it could discriminate only one-base mismatched microRNA sequence. Moreover, the down-regulated expression of microRNA-21 in DF-1 chicken fibroblast cells infected with subgroup J avian leukemia virus (ALVs) was confirmed by the developed method, indicating that microRNA-21 might be a new biomarker for avian leukemia. This work opens a different perspective for microRNAs detection and early diagnose of avian leukemia.
Co-reporter:Yunlei Zhou, Zhenning Xu, Mo Wang, Bing Sun, Huanshun Yin, Shiyun Ai
Biosensors and Bioelectronics 2014 Volume 53() pp:263-267
Publication Date(Web):15 March 2014
DOI:10.1016/j.bios.2013.09.065
•A visible light-activated photoelectrochemical biosensor based on BiOI was fabricated.•The biosensor was used to detect DNA methyltransferase activity.•Methyl binding domain (MBD1) protein was used to recognize methylated DNA.•This method showed high detection sensitivity with detection limit of 0.035 unit/mL.•The fabricated biosensor could be used to screen inhibitors.DNA methylation has important roles in gene regulation and relates to some diseases, especially cancers. Because DNA methylation is catalyzed by DNA methyltransferases (MTase), it is important to detect the activity of DNA MTase. In this work, we developed a novel visible light-activated photoelectrochemical (PEC) biosensor for DNA MTase activity assay, whereby bismuth oxyiodide (BiOI) nanoflake was synthesized as photoactive electrode material, M. SssI MTase as methylation reagent and methyl binding domain protein (MBD1 protein) as methylation recognition element. After cytosine methylation event occurred at the site of 5′-CG-3′, it could be probed by MBD1 protein and this protein could be combined tightly with methylated cytosine, which would lead to a decreased photocurrent due to the hindrance towards electron donor transferring to electrode surface by huge-volume protein. The decreased photocurrent was proportional to M. SssI MTase concentration from 0.1 to 50 unit/mL with the detection limit of 0.035 unit/mL (S/N=3). This detection limit was lower than that in some previous reports. This PEC biosensor showed high selectivity and good reproducibility for M. SssI MTase assay. Moreover, this method was successfully applied also to screen DNA MTase inhibitors, indicating that this PEC biosensor could be an alternative platform in anti-cancer pharmaceuticals discovery.
Co-reporter:Bing Sun, Fengmin Qiao, Lijian Chen, Zhen Zhao, Huanshun Yin, Shiyun Ai
Biosensors and Bioelectronics 2014 Volume 54() pp:237-243
Publication Date(Web):15 April 2014
DOI:10.1016/j.bios.2013.11.021
•Inerratic Bi2S3 nanorods were synthesized through a facial solvothermal method.•As-prepared Bi2S3 nanorods exhibited brilliant photoelectrochemical response.•ALP catalytic chemistry was utilized for the in situ AA production and electron donating.•An effective photoelectrochemical immunosensor was fabricated based on the signal-on strategy.•The proposed immunosensor depicted high sensitivity and specificity for ALVs-J detection.A universal and effective photoelectrochemical (PEC) immunosensing device was fabricated on an indium tin oxide (ITO) electrode for sensitive and specific detection of subgroup J of avian leukosis virus (ALVs-J) based on a signal-on strategy. Bismuth sulfide (Bi2S3) nanorods, with good morphology, high crystallinity and differentiated PEC properties, were selected as the photoelectrochemical species and synthesized by a facile hydrothermal method. On the basis of alkaline phosphatase catalytic chemistry to in situ produce ascorbic acid for electron donating, an enhanced photocurrent was obtained. Due to the dependence of the photocurrent signal on the concentration of generated electron donor, an exquisite immunosandwich protocol was successfully constructed for PEC detection of ALVs-J with a linear range from 102.14 to 103.65 TCID50/mL. The detection limit was 102.08 TCID50/mL (S/N=3), and high stability and specificity were obtained. The strategy provides a fast and sensitive method for ALVs-J analysis and opens a general format for future development of PEC immunoanalysis.
Co-reporter:Yunlei Zhou, Mo Wang, Zhenning Xu, Cailing Ni, Huanshun Yin, Shiyun Ai
Biosensors and Bioelectronics 2014 Volume 54() pp:244-250
Publication Date(Web):15 April 2014
DOI:10.1016/j.bios.2013.11.026
•We developed a simple, sensitive, and label-free method for microRNAs biosensing.•This method was based on mimic enzyme catalysis signal amplification.•Carboxylic graphene–hemin hybrid nanosheets was synthesized and used as minic enzyme.•The biosensor showed high sensitivity with the detection limit of 0.17 pM.•Abscisic acid influences microRNA-159a expression in Arabidopsis thaliana seedlings.MicroRNAs (miRNAs) play very important roles in plant growth and development as well as phytohormones. More importantly, microRNAs were recently found to be a new growth regulator involved in plant hormone signaling. Therefore, for investigating the expression change of microRNAs in plants exposed to phytohormones and understanding the effect of phytohormones on microRNAs expression, we developed a simple, sensitive, and label-free method for microRNAs biosensing based on mimic enzyme catalysis signal amplification, where carboxylic graphene–hemin hybrid nanosheets was synthesized and used to catalyze the oxidation reaction of hydroquinone in the presence of H2O2 due to the intrinsic peroxidase-like activity of hemin on the carboxylic graphene surface. The electrochemical reduction current of the oxidative product of benzoquinone was depended on the hybridization amount of microRNAs and used to monitor the microRNAs hybridization event. Under optimal detection conditions, the current response was proportional to the logarithm concentration of microRNA-159a from 0.5 pM to 1.0 nM with the detection limit of 0.17 pM (S/N=3). The fabricated biosensor showed highly reproducible (Relative standard deviation (RSD) was 3.53% for 10 biosensors fabricated independently) and detection selectivity (Even discriminating single-base mismatched microRNA sequence). We also found that abscisic acid, a kind of phytohormone, had greatly influence on microRNA-159a expression in Arabidopsis thaliana seedlings. With increasing abscisic acid concentration and prolonging incubation time, both the expression level of microRNA-159a increased. This graphene–hemin-based approach provides a novel avenue to detect microRNA with high sensitivity and selectivity while avoiding laborious label, disadvantages of bio-enzymes and complex operations for microRNAs separation and enrichment, which might be attractive for genetic analysis and clinic biomedical application.
Co-reporter:Bing Sun, Lijian Chen, Yan Xu, Min Liu, Huanshun Yin, Shiyun Ai
Biosensors and Bioelectronics 2014 Volume 51() pp:164-169
Publication Date(Web):15 January 2014
DOI:10.1016/j.bios.2013.07.027
•A novel MPA-CdS/RGO nanocomposite was synthesized via a facile solverthermal method.•The MPA-CdS/RGO nanocomposite exhibited enhanced photocurrent.•A photoelectrochemical immunosensor was fabricated based on the MPA-CdS/RGO nanocomposites.•The strategy could be used for rapid detection of IAA with high sensitivity and specificity.A novel ultrasensitive photoelectrochemical immunosensor was fabricated based on 3-mercaptopropionic acid stabilized CdS/reduced graphene oxide (MPA-CdS/RGO) nanocomposites for indole-3-acetic acid (IAA) detection. The MPA-CdS/RGO nanocomposites were synthesized by in situ solvothermal growth of triangulated pyramidal CdS nanoparticles on the RGO sheet. 3-Mercaptopropionic acid (MPA) was employed as the modifier and bridge to immobilize the antibody. The nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and UV/vis spectra. The results showed that the MPA-CdS/RGO nanocomposites revealed enhanced photocurrent response due to excellent electron transport properties of RGO and the improved assembly of CdS nanoparticles onto RGO sheet with the introduction of MPA. Based on the dependence of the photocurrent decline on the concentration of IAA, the proposed photoelectrochemical immunosensor for IAA depicted a linear range from 0.1 to 1000 ng/mL with a lower detection limit (0.05 ng/mL). The high sensitivity, reproducibility and specificity of the method permitted the method suitable to be used in real samples.
Co-reporter:Huanshun Yin, Bing Sun, Yunlei Zhou, Mo Wang, Zhenning Xu, Zhengliang Fu, Shiyun Ai
Biosensors and Bioelectronics 2014 Volume 51() pp:103-108
Publication Date(Web):15 January 2014
DOI:10.1016/j.bios.2013.07.040
•DNA methylation was detected by a novel photoelectrochemical (PEC) immunosensor.•The photoelectrochemical signal was produced by Bi2S3 nanoparticles.•Methylated DNA was recognized by methyl bonding domain (MBD) protein.•The photoelectrochemical signal decreased after capturing MBD protein and his-tag antibody.•The immunosensor showed a low detection limit of 3.5×10–14 M.In this work, we fabricated a novel photoelectrochemical immunosensor for assay of DNA methylation, where Bi2S3 nanorods were used as photoelectric conversion material, MBD1 protein (a kind of methyl bonding domain protein) was used as DNA methylation recognizing unit, anti-his tag antibody was used to further inhibit the photocurrent and increase the detection sensitivity. The results demonstrated that Bi2S3 possessed excellent photoelectron property. The detection conditions, such as Bi2S3 concentration, MBD1 protein concentration, incubation time of MBD1 protein, antibody concentration and antibody incubation time, were optimized. Under optimal experimental conditions, the photocurrent variation was proportional to the logarithm of methylated target DNA concentration from 10−9 to 10–13 M with detection limit of 3.5×10–14 M (S/N=3). Moreover, the immunosensor presented high detection specificity, even distinguishing single-base mismatched sequence.
Co-reporter:Lijian Chen, Kaifang Sun, Peipei Li, Xianzhong Fan, Jianchao Sun and Shiyun Ai
Nanoscale 2013 vol. 5(Issue 22) pp:10982-10988
Publication Date(Web):27 Aug 2013
DOI:10.1039/C3NR03031H
LDH nanosheets were obtained via continuous impaction and exfoliation by herring sperm DNA molecules using a constant vibration method. DNA–LDH nanohybrids were composed by electrostatic forces and they exhibited DNA-enhanced peroxidase-like activity. The morphology and structure of DNA–LDH nanohybrids were analyzed by transmission electron microscopy (TEM), selected-area electron diffraction (SAED), X-ray diffraction (XRD), and atomic force microscopy (AFM) characterization. On the basis of the high catalytic activity of DNA/CuAl–LDH nanosheets, a rapid, sensitive, and convenient approach was developed for colorimetric detection of H2O2 and blood glucose. This method can be potentially applied in medical diagnostics and biotechnology fields.
Co-reporter:Lijian Chen, Bing Sun, Xindong Wang, Fengmin Qiao and Shiyun Ai
Journal of Materials Chemistry A 2013 vol. 1(Issue 17) pp:2268-2274
Publication Date(Web):01 Mar 2013
DOI:10.1039/C3TB00044C
In this report, a novel approach for exfoliation of Co–Al layered double hydroxides (LDHs) in aqueous solution of L-asparagine was proposed. L-Asparagine is a water-soluble amino acid whose carbonyl groups would have a strong interaction with the LDH host layers and the amino groups might weaken the interlayer interactions. This simple method did not need reflux at high temperature, overcame the drawback of using organic solvents, and even resulted in a stably stored colloidal suspension of 2D nanosheets. Besides, the peroxidase-like activity of the exfoliated Co–Al LDH (Co–Al ELDH) was enhanced compared with unexfoliated LDH. Co–Al ELDH could rapidly catalyze oxidation of the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2, producing a blue color reaction. On this basis, simple, rapid and selective colorimetric methods for H2O2 and glucose detection were developed. The presented means was used for glucose detection in fruit juices and fine results were obtained.
Co-reporter:Jing Dong, Xianzhong Fan, Fengmin Qiao, Shiyun Ai, Hao Xin
Analytica Chimica Acta 2013 Volume 761() pp:78-83
Publication Date(Web):25 January 2013
DOI:10.1016/j.aca.2012.11.042
This paper proposed a novel method for ultra-trace detection of pesticides combining electrochemical reduction of Ellman's reagent with acetylcholinesterase (AChE) inhibition. The amperometric biosensor, fabricated by immobilizing AChE on multi-walled carbon nanotubes-chitosan (MWCNTs-Chi) nanocomposites modified glassy carbon electrode, enjoyed high sensitivity owing to the excellent conductivity and favourable biocompatibility of MWCNTs-Chi nanocomposites. Meanwhile, the sensitivity of the biosensor was further enhanced using the electrochemical reduction signal of DTNB for determination. Under optimum conditions, methyl parathion was detected based on its inhibition effect on AChE activity and the subsequent change in electrochemical reduction response of DTNB. Good relationship was obtained between the reduction current and pesticide concentration in the ranges of 5.0 × 10−7 to 1.0 × 10−12 M with a detection limit of 7.5 × 10−13 M (S/N = 3). Moreover, the proposed protocol was successfully employed for the determination of methyl parathion in water and soil samples.Graphical abstractHighlights► A novel method was proposed for ultra-trace detection of pesticides. ► This method combined electrochemical reduction of DTNB with AChE inhibition. ► The fabricated biosensor determined methyl parathion with high sensitivity. ► The developed biosensor was used in real samples with satisfactory results.
Co-reporter:Zhenning Xu, Mo Wang, Huanshun Yin, Shiyun Ai, Liang Wang, Junling Pang
Electrochimica Acta 2013 Volume 112() pp:596-602
Publication Date(Web):1 December 2013
DOI:10.1016/j.electacta.2013.09.037
•We presented an electrochemical method for assay of DNA MTase activity.•It was based on DNA methylation-sensitive cleavage method.•It was used DNA-Au bio bar code and HRP to amplify signals.•Four DNA MTase inhibitors were investigated to study on the assay.A sensitive electrochemical method for detection of DNA methylation and assay of DNA methyltransferase (Dam) was investigated based on methylation-sensitive restriction endonuclease, DNA-Au bio bar code and enzymatic signal amplification. After the DNA probe was hybridized with complementary DNA sequence, and the obtained double-strand DNA (dsDNA) was further methylated by Dam MTase, it could be successively digested by Dpn I at the methylated sites. As a result, the bio bar code and streptavidin-horseradish peroxidase (S-HRP) could not be conjugated on the electrode surface through the specific interaction between biotin and S-HRP, where biotin was labeled at the DNA-Au bio bar code. Thus, only a low electrochemical reduction signal was obtained. However, the hybridized probe could hybrid with DNA-Au bio bar code, and then S-HRP could be conjugated on the electrode surface in the absence of Dam MTase and Dpn I, so a larger reduction current of enzymatic product was obtained. The change of the reduction current of enzymatic product was used to detect DNA methylation and Dam MTase activity. The detection limit of Dam MTase was 0.02 unit/mL (S/N = 3). Moreover, the inhibitions of mitomycin C, paclitaxel, chlorogenic acid and epicatechin were also investigated. Therefore, this method provided a sensitive platform for monitoring DNA methylation and DNA MTase activity.
Co-reporter:Xiaomeng Meng, Zhenning Xu, Mo Wang, Huanshun Yin, Shiyun Ai
Electrochimica Acta 2013 Volume 95() pp:200-204
Publication Date(Web):15 April 2013
DOI:10.1016/j.electacta.2013.02.050
Co-reporter:Huanshun Yin, Zhenning Xu, Mo Wang, Xueping Zhang, Shiyun Ai
Electrochimica Acta 2013 Volume 89() pp:530-536
Publication Date(Web):1 February 2013
DOI:10.1016/j.electacta.2012.11.093
DNA methylation plays a crucial role in eukaryotes’ growth and development, which is catalyzed by DNA methyltransferase (MTase). DNA MTase can transfer the methyl group to the C-5 position of cytosine in eukaryote from the methyl group donor of S-adenosylmethionine (SAM). Here, we developed a sensitive electrochemical method for assay of DNA methyltransferase (MTase) activity and screening of DNA MTase inhibitor without labeling processes. This strategy is mainly based on the change of reduction peak current of ferrocenecarboxylic acid (FcA), which is conjugated to the biosensor as electrochemical activity probe. The reduction current of FcA was enhanced with increasing DNA MTase concentration from 0.1 to 70 unit/mL, where the linear range of the concentration was from 0.1 to 1 unit/mL and 1 to 50 unit/mL with the detection limit of 0.045 unit/mL (S/N = 3). The investigation results demonstrated that the activity of DNA MTase depended on MTase concentration and incubation time. Inhibition experiment indicated that fisetin had good inhibition activity on DNA MTase in the presence of catechol-O-methyltransferase. This electrochemical method had the potential application in the screening of DNA MTase inhibitor, provided valuable information for anti-cancer drug research and also for cancer therapy.Graphical abstractHighlights► An electrochemical method was developed for DNA methylation detection. ► The developed method can assay DNA methyltransferase (MTase) activity. ► The fabricated sensor can be used for monitoring of the inhibitory effect on MTase.
Co-reporter:Xiaomeng Meng, Yunlei Zhou, Qianjin Liang, Xiangjin Qu, Qingqing Yang, Huanshun Yin and Shiyun Ai
Analyst 2013 vol. 138(Issue 12) pp:3409-3415
Publication Date(Web):28 Mar 2013
DOI:10.1039/C3AN36788F
A simple and novel microRNA (miRNA) biosensor was developed using DNA-Au bio bar code (DNA-Au) and G-quadruplex-based DNAenzyme. DNA-Au increased the amount of miRNA-21 participating in hybridization. Hemin/G-quadruplex DNAenzyme significantly improved the catalysis of H2O2 by oxidation of hydroquinone, resulting in an obvious reduction current of benzoquinone for miRNA-21 indirect detection. Under optimum conditions, the linear relationship between miRNA-21 concentration and reduction response was obtained with the detection limit of 0.006 pM, which showed a good sensitivity. Besides, selectivity of the biosensor was investigated by detecting the base mismatched miRNAs. This proposed method was further applied to detect miRNA-21 extracted from human hepatocarcinoma BEL-7402 cells and human mastocarcinoma MCF-7 cells. The influence of bisphenol A (BPA) on the expression of miRNA-21 in cells was also investigated. The biosensor performs well in practical applications, which suggests it may provide a new platform for gene diagnosis.
Co-reporter:Haichao Su, Han Zhao, Fengmin Qiao, Lijian Chen, Ruihuan Duan and Shiyun Ai
Analyst 2013 vol. 138(Issue 10) pp:3026-3031
Publication Date(Web):13 Mar 2013
DOI:10.1039/C3AN00026E
The presence of Escherichia coli (E. coli) in food and drinking water is a chronic problem worldwide. Protecting food against bacterial contamination and rapid diagnosis of infection require simple and rapid assays for detection of bacterial pathogens, including E. coli O157:H7. Here we report a rapid and novel colorimetric method for detecting E. coli O157:H7. This colorimetric method is based on the catalytic oxidation of the peroxidase substrate 3,3,5,5-tetramethylbenzidine by hydrogen peroxide using 4-mercaptophenylboronic acid-functioned Au@Pt nanoparticles adsorbed on the surface of E. coli O157:H7. The assay showed excellent sensitivity both with the naked eye and based on absorbance measurements. The absorbance at 652 nm was proportional to the concentration of E. coli O157:H7 ranging from 7 to 6 × 106 cfu mL−1 with a limit of detection of 7 cfu mL−1. The total detection time was less than 40 min.
Co-reporter:Xindong Wang, Jing Dong, Huami Ming and Shiyun Ai
Analyst 2013 vol. 138(Issue 4) pp:1219-1225
Publication Date(Web):12 Dec 2012
DOI:10.1039/C2AN36297J
A novel strategy was proposed for preparing a highly sensitive glycoprotein sensor based on molecularly imprinted polymers (MIP), which was electropolymerized with o-phenylenediamine and 3-aminophenylboronic acid monohydrate in the presence of template molecules (bovine serum albumin (BSA)). Sensitivity improved dramatically owing to the application of a graphene–Au nanoparticles hybrid as the electrode modifier, and the immobilization of a large amount of 6-ferrocenylhexanethiol, as the electroactive species, onto nanoparticles. The quantification of BSA was realized by detecting the electrochemical oxidation signal of 6-ferrocenylhexanethiol, which was bonded onto the electrode. Under optimized conditions, a good relationship was obtained between the response current and logarithm of BSA concentration in the range of 1.0 × 10−11 to 1.0 × 10−5 g mL−1 with a detection limit of 7.5 × 10−12 g mL−1 (S/N = 3). The resulting MIP sensor displayed good selectivity, reproducibility and stability.
Co-reporter:Huanshun Yin, Zhenning Xu, Yunlei Zhou, Mo Wang and Shiyun Ai
Analyst 2013 vol. 138(Issue 6) pp:1851-1857
Publication Date(Web):09 Jan 2013
DOI:10.1039/C3AN36526C
A label-free electrochemical immunosensor for ultra-sensitive detection of indole-3-acetic acid (IAA), a very important phytohormone, has been developed in this work. The detection strategy was mainly based on 4-aminophenylboronic acid, magnetic nanoparticles functionalized with horseradish peroxidase-conjugated goat anti-rat immunoglobulin G (HRP-IgG-Fe3O4) and rat monoclonal antibody against IAA-modified gold nanoparticles (anti-IAA-AuNPs). HRP-IgG-AuNPs was covalently assembled on the electrode surface through the specific chemical reaction between boronic acid and the vicinal diol in HRP-IgG. Then, anti-IAA-AuNPs was further assembled on the electrode via the interaction between IgG and antibody. Through the dual amplification of HRP-IgG-Fe3O4 and anti-IAA-AuNPs, the trapping capacity of the immunosensor for IAA was significantly enhanced based on the promotion of the immunoreaction between antibody and antigen, which resulted in a large decrease of the electrochemical response of the redox probe, Fe(CN)63−, and an increase in sensitivity. The developed electrochemical immunosensor exhibited a wide linear range from 0.02 to 500 ng mL−1 with a low detection limit of 0.018 ng mL−1 (S/N = 3). Moreover, the proposed immunosensor showed acceptable selectivity, reproducibility, accuracy and stability. The IAA extracted from various seeds was successfully detected using the developed immunosensor. This assay method might provide an alternative strategy for the detection of various phytohormones.
Co-reporter:Kun Shang, Bing Sun, Jianchao Sun, Jun Li and Shiyun Ai
New Journal of Chemistry 2013 vol. 37(Issue 8) pp:2509-2514
Publication Date(Web):16 May 2013
DOI:10.1039/C3NJ00148B
A novel poly-(3-thiopheneacetic acid) coated Fe3O4@LDHs photocatalyst was prepared and used for the photocatalytic disinfection of bacteria under solar light irradiation. The influencing parameters of the photocatalytic antibacterial activity of the Fe3O4@PTAA-LDHs photocatalyst were optimized against E. coli and S. aureus. Results showed that the Fe3O4@PTAA-LDHs photocatalyst could effectively absorb ultraviolet and visible light. The antibacterial rate could achieve 99.99% when irradiated by solar light with 0.8 mg mL−1 Fe3O4@PTAA-LDHs during 140 min. Moreover, it was confirmed that the ˙OH were generated during the photocatalytic process, which was the major reason for the photocatalytic disinfection. The structural destruction of the bacteria cells that occurred during the bactericidal procedure was observed by TEM images. The novel photocatalyst could have potential applications in the related bactericidal fields.
Co-reporter:Peng Ju, Hai Fan, Bingliang Zhang, Kun Shang, Tao Liu, Shiyun Ai, Dun Zhang
Separation and Purification Technology 2013 Volume 109() pp:107-110
Publication Date(Web):9 May 2013
DOI:10.1016/j.seppur.2013.01.057
•Novel SVO nanomaterials for photocatalytic degradation BPA under visible light irradiation.•Ag/AgVO3 was visible-light-sensitive photocatalyst.•Ag/AgVO3 was effective and stable after using 8 cycles.•Hydroxyl radicals played a key role in the photocatalytic degradation reaction.A novel composite nanomaterial of Ag/AgVO3 was prepared and the photocatalytic activity for the degradation of bisphenol A was investigated under visible light irradiation. Experimental results showed that Ag/AgVO3 exhibited higher photocatalytic activity than bare β-AgVO3 under visible light irradiation. The degradation efficiency of BPA by Ag/AgVO3 could reach 100% within 150 min. The obvious enhancement of photocatalytic activity by Ag nanoparticles could be attributed to the synergetic effects between noble metal and semiconductor. Furthermore, hydroxyl radicals (OH) played a key role in the photocatalytic reaction and a possible mechanism of the synergistic system was proposed.
Co-reporter:Jing Dong, Han Zhao, Fengmin Qiao, Pei Liu, Xindong Wang and Shiyun Ai
Analytical Methods 2013 vol. 5(Issue 11) pp:2866-2872
Publication Date(Web):09 Apr 2013
DOI:10.1039/C3AY26599D
We have fabricated a sensitive acetylcholinesterase biosensor that is based on dual-signal amplification. A large amount of enzyme was immobilized on a glassy carbon electrode via specific binding between functionalized ZnSe quantum dots and acetylcholinesterase, and a graphene–chitosan nanocomposite was introduced that improves the response. These two factors render the biosensor highly sensitive to acetylthiocholine chloride. Organophosphate pesticides were detected with this biosensor using methyl parathion as a model enzyme inhibitor. Under optimal conditions, there is a linear relationship between the percentage of inhibition (I%) and the log of the concentration of methyl parathion in the 0.5 nM to 0.5 μM range, with a 0.2 nM detection limit (at an S/N of 3). The biosensor displays acceptable reproducibility and relatively good storage stability. It was successfully employed to the determination of methyl parathion in spiked water and soil samples.
Co-reporter:Bing Sun, Zhi Qiao, Kun Shang, Hai Fan, Shiyun Ai
Materials Letters 2013 Volume 91() pp:142-145
Publication Date(Web):15 January 2013
DOI:10.1016/j.matlet.2012.09.074
In this paper, novel uniformly distributed silver sulfide/bismuth sulfide nanocomposites (Ag2S/Bi2S3 NCs) were prepared by using one-step method for the photocatalytic inactivation against Gram-negative bacteria Escherichia coli (E. coli) under solar light irradiation. The results showed that Ag2S/Bi2S3 NCs simultaneously had uniform platelets and coralloid particles with regular shape and perfect dispersion properties and could render the capability of absorbing a broad solar spectrum. The antibacterial tests demonstrated that higher bactericidal rate was obtained with 1.0 mg/mL of Ag2S/Bi2S3 NCs under solar light irradiation during 100 min at 37 °C. It was confirmed by using fluorescence method that hydroxyl radicals generated in the photocatalytic process were the major responsibility for the photoinactivation. This work provides a promising photocatalyst in the bactericidal fields.Highlights► Novel Ag2S/Bi2S3 nanocomposites were prepared by one-step method. ► Ag2S/Bi2S3 nanocomposites could be activated by absorbing a broad solar spectrum. ► Ag2S/Bi2S3 displayed excellent antibacterial activity against Escherichia coli. ► Hydroxyl radicals were confirmed to be the major responsibility for the photoinactivation.
Co-reporter:Bing Sun, Kun Zhang, Lijian Chen, Lintong Guo, Shiyun Ai
Biosensors and Bioelectronics 2013 Volume 44() pp:48-51
Publication Date(Web):15 June 2013
DOI:10.1016/j.bios.2013.01.014
A universal photoelectrochemical (PEC) sensing platform was fabricated based on the composition of protoporphyrin IX (PPIX), tungsten trioxide (WO3) and reduced graphene oxide (rGO) on indium tin oxide (ITO) electrode for detecting cysteine in aqueous solution. The rGO layer was not only providing bridges for the ITO electrode to anchor tightly with the WO3 nanostructures, but behaved as an electron transfer medium to enhance the electron transport from the conduction band (CB) of WO3. Furthermore, the strong absorption coefficient of porphyrin adsorbed onto WO3 nanoplates by bidentate binding could significantly improve the photocurrent density and slow charge recombination kinetics through the ultrafast electron injection. The SEM, XRD, and DRS were employed to characterize the prepared nanomaterials and modified-ITO electrodes. The results showed that the PPIX–WO3–rGO/ITO electrode could render the capability of absorbing a broad UV–vis light and displayed excellent photocurrent response in 0.1 M pH 7.0 PBS with excitation wavelength at 380 nm, which could be notably improved upon addition of cysteine at 0.3 V. Based on the enhanced photocurrent signal, a novel method for PEC detection of cysteine was developed with a linear range of 0.1 to 100 μM in 0.1 M PBS (pH 7.0). The detection limit was 25 nM (3σ). And higher stability and selectivity were obtained. The novel strategy could provide a fast and sensitive method for cysteine analysis.Graphical abstractHighlights► A universal PEC sensing platform was fabricated based on a ternary composition of PPIX–WO3–rGO. ► The multiple electron transfer system of PPIX–WO3–rGO obtained enhanced photocurrent. ► A highly sensitive and selective biosensor for PEC detection of cysteine developed. ► The proposed PEC sensor opened up a new avenue to the application of WO3 nanostructures.
Co-reporter:Huanshun Yin, Yunlei Zhou, Zhenning Xu, Lijian Chen, Di Zhang, Shiyun Ai
Biosensors and Bioelectronics 2013 Volume 41() pp:492-497
Publication Date(Web):15 March 2013
DOI:10.1016/j.bios.2012.09.010
DNA methylation is one of important epigenetics events, and responsible to transcription, genomic imprinting and cellular differentiation. Aberrant DNA methylation is always contacted with various diseases. Methyl binding domain (MBD) proteins can specifically bind to the methylated CpG dinucleotides. Conventional assay for DNA methylation normally need bisulfide treatment, methylated nucleotide labeling or PCR amplification. Here, we fabricated a novel electrochemical biosensor for detection of DNA methylation, assay of DNA methyltransferase (MTase) activity and screening of MTase inhibitor based on MBD protein and coomassie brilliant blue G250 (CBB-G250), where the electrochemical signal of CBB-G250 was used to monitor the methylation event. After the hybrids of DNA S1 and DNA S2 were treated with M. SssI MTase in the presence of S-adenosylmethionine, the MBD proteins were specifically conjugated to the methylation site of CpG dinucleotides, and then, the MBD proteins were stained with CBB-G250. The electrochemical signal of CBB-G250 increased linearly with increasing M. SssI MTase concentration in the range from 0.1 to 40 unit/mL. Furthermore, the inhibition investigation demonstrates that fisetin and chlorogenic acid can inhibit the M. SssI MTase activity with the IC50 value of 153.12 and 137.07 μM, respectively. Therefore, we think that this study may provide a sensitive platform for screening of DNA MTase inhibitors.Highlights► We develop a novel electrochemical method for MTase assay. ► Methyl binding domain protein was used as recognition unit of methylation site. ► Coomassie brilliant blue was used as electroactive label. ► A low detection limit of MTase was 0.04 unit/mL. ► This method provided information on screening of MTase inhibitor.
Co-reporter:Xindong Wang, Lijian Chen, Xiurong Su, Shiyun Ai
Biosensors and Bioelectronics 2013 Volume 47() pp:171-177
Publication Date(Web):15 September 2013
DOI:10.1016/j.bios.2013.03.021
•Ultrasensitive immunoassay of avian leukosis virus subgroup J was achieved.•Graphene quantum dots were used for the conjugation of antibodies.•Apoferritin-encapsulated Cu nanoparticles were selected as electroactive probes.•The strategy provides a great promise in clinical application.A novel sandwich electrochemical immunoassay was developed for ultrasensitive detection of avian leukosis virus subgroup J (ALVs-J) using graphene quantum dots (GQDs) and apoferritin-encapsulated Cu (Cu-apoferritin) nanoparticles for signal amplification. GQDs were used both for the conjugation of primary ALVs-J antibodies (Ab1), and immobilization of secondary ALVs-J antibodies (Ab2) after compounded with Fe3O4. Cu-apoferritin nanoparticles were first selected to immobilize onto Fe3O4@GQDs hybrid as electroactive probes. After the well-known sandwich-type assembly, Cu was released from the apoferritin cavity, and then detected by differential pulse voltammetry (DPV). Owing to the huge surface area GQDs provided, a considerable number of antibodies were loaded onto the immunosensor, which effectively increased the electrical signal. And the introduction of Cu-apoferritin nanoparticles increased the loading amount of electroactive probes significantly; hence the signal was once again amplified. To embody the signal amplification property of the protocol, the performance of various labels was compared in detail. The immunosensor displayed excellent analytical performance for the detection of ALVs-J range from 102.08 to 104.50 TCID50/mL with a detection limit of 115 TCID50/mL (S/N=3), and the resulting immunosensor also showed high sensitivity, good reproducibility and stability.
Co-reporter:Kun Shang, Xindong Wang, Bing Sun, Ziqiang Cheng, Shiyun Ai
Biosensors and Bioelectronics 2013 Volume 45() pp:40-45
Publication Date(Web):15 July 2013
DOI:10.1016/j.bios.2013.01.049
A novel sandwich-type electrochemical immunosensor was fabricated for ultrasensitive detection of subgroup J of avian leukosis virus (ALVs-J) by employing β-cyclodextrin-ferrocene (CD-Fc) host–guest complex multifunctional Fe3O4 nanospheres as labels and β-cyclodextrin functional graphene sheets (CD-GS) nanocomposite as sensor platform. The sensitivity was greatly improved based on the triple amplification strategy. Firstly, the CD-GS improved the electron transfer rate as well as increasing the surface area to capture a large amount of primary antibodies (Ab1). Secondly, the CD on the Fe3O4 surface with strong recognition capability could form stable CD-Fc host–guest inclusion complex and provided larger free room for the conjugation of secondary antibodies (Ab2) and glucose oxidase (GOD). Finally, the conjugated GOD exhibited extraordinary electrochemical biocatalysis towards the reduction reaction of Fc+ by glucose. Under the optimized conditions, the electrochemical immunosensor exhibited a wide working range from 102.27–103.50 TCID50/mL (TCID50: 50% tissue culture infective dose) with a low detection limit of 102.19 TCID50/mL (S/N=3). The selectivity, reproducibility, and stability are acceptable. The assay was evaluated for real avian serum sample, receiving satisfactory results. This new type of triple amplification strategy may provide potential applications for the clinic application.Graphical abstractHighlights► Subgroup J of avian leukosis virus were detected by ultrasensitive electrochemical immunnoassay technology. ► β-cyclodextrin-ferrocene host–guest complex multifunctional Fe3O4 nanospheres were used as labels. ► β-cyclodextrin functional graphene sheets nanocomposite was used for the immunosensor platform. ► The extreme enhancement of the sensitivity was greatly improved based on the triple amplification strategy.
Co-reporter:Lijian Chen;Na Wu;Bing Sun;Haichao Su;Shiyun Ai
Microchimica Acta 2013 Volume 180( Issue 7-8) pp:573-580
Publication Date(Web):2013 June
DOI:10.1007/s00604-013-0958-y
We describe a rapid and convenient colorimetric method for the detection of oxidative DNA damage caused by peroxynitrite (ONOO−) using unmodified gold nanoparticles (AuNPs). AuNPs are stable in the presence of single-stranded DNA (ssDNA) against the aggregation induced by a high ionic strength. If adsorbed ssDNA are cleaved by ONOO− to form smaller fragments, the AuNPs rapidly aggregate due to electrostatic attraction. As a result, the color of the solution changes from red to blue, and this can be seen with bare eyes. We also have evaluated the activity of the antioxidants gallic acid, ascorbic acid and caffeic acid to scavenge ONOO−. This method therefore also can be applied to screen for anti-oxidation drugs and agents.
Co-reporter:Huanshun Yin, Yunlei Zhou, Zhenning Xu, Mo Wang, Shiyun Ai
Biosensors and Bioelectronics 2013 Volume 49() pp:39-45
Publication Date(Web):15 November 2013
DOI:10.1016/j.bios.2013.04.040
•An electrochemical method was developed for screening DNA MTase activity and inhibition.•It was based on MeCP2 protein and anti-His tag coupled with HRP-assisted amplification.•This strategy exhibited high sensitivity and excellent selectivity toward M. SssI MTase.•It is a label-free, sensitive method for the detection of DNA MTase activity.•The screening of the inhibitors of DNA MTase can be achieved based on the assay.In this work, we fabricated a novel electrochemical immunosensor for detection of DNA methylation, analysis of DNA MTase activity and screening of MTase inhibitor. The immunosensor was on the basis of methyl binding domain protein of MeCP2 as DNA CpG methylation recognization unit, anti-His tag antibody as “immuno-bridge” and horseradish peroxidase labeled immuneglobulin G functionalized gold nanoparticles (AuNPs–IgG–HRP) as signal amplification unit. In the presence of M. SssI MTase, the symmetrical sequence of 5′-CCGG-3′ was methylated and then recognized by MeCP2 protein. By the immunoreactions, anti-His tag antibody and AuNPs–IgG–HRP was captured on the electrode surface successively. Under the catalysis effect of HRP towards hydroquinone oxidized by H2O2, the electrochemical reduction signal of benzoquinone was used to analyze M. SssI MTase activity. The electrochemical reduction signal demonstrated a wide linear relationship with M. SssI concentration ranging from 0.05 unit/mL to 90 unit/mL, achieving a detection limit of 0.017 unit/mL (S/N=3). The most important advantages of this method were its high sensitivity and good selectivity, which enabled the detection of even one-base mismatched sequence. In addition, we also verified that the developed method could be applied for screening the inhibitors of DNA MTase and for developing new anticancer drugs.
Co-reporter:Zhenning Xu, Mo Wang, Tingting Zhou, Huanshun Yin, Shiyun Ai
Sensors and Actuators B: Chemical 2013 178() pp: 412-417
Publication Date(Web):
DOI:10.1016/j.snb.2012.12.124
Co-reporter:Mo Wang, Zhenning Xu, Lijian Chen, Huanshun Yin, and Shiyun Ai
Analytical Chemistry 2012 Volume 84(Issue 21) pp:9072
Publication Date(Web):October 2, 2012
DOI:10.1021/ac301620m
In this paper, we developed a novel electrochemical method to quantify DNA methyltransferase (MTase) and analyze DNA MTase activity. After the double DNA helix structure was assembled on the surface of gold nanoparticle modified glassy carbon electrode, it was first methylated by M. SssI MTase and then digested by restriction endonuclease HpaII, which could not recognize the methylated CpG site. Successively, anti-5-methylcytosine antibody was specifically conjugated on the CpG methylation site and horseradish peroxidase labeled goat antimouse IgG (HRP-IgG) was conjugated on anti-5-methylcytosine antibody. In the detection buffer solution containing H2O2 and hydroquinone, HRP-IgG can catalyze hydroquinone oxidation by H2O2 to generate benzoquinone, resulting in a highly electrochemical reduction signal. Consequently, the activity of M. SssI MTase was assayed, and DNA methylation was detected using the signal change with and without methylation. Furthermore, the inhibition investigation demonstrated that, in the presence of 160 μM S-adenosyl-l-methionine as methyl donor, 5-aza-2′-deoxycytidine, procaine, epicatechin, and caffeic acid could inhibit the M. SssI MTase activity with the IC50 values of 45.77, 410.3, 129.03, and 124.2 μM, respectively. Therefore, this study may provide a sensitive platform for screening DNA MTase inhibitors.
Co-reporter:Xiaomeng Meng, Minrong Xu, Jianying Zhu, Huanshun Yin, Shiyun Ai
Electrochimica Acta 2012 Volume 71() pp:233-238
Publication Date(Web):1 June 2012
DOI:10.1016/j.electacta.2012.03.143
In this paper, a novel sensitive biosensor was fabricated for DNA detection based on gold nanoparticles (AuNPs) locked nucleic acid modified hairpin DNA probe (LNA-m-HpDNA) and enzymatic signal amplification. LNA-m-HpDNA dually labeled with 3′-thiol and 5′-biotin was efficiently assembled on the electrode via the interaction of thiol and gold. The stem-loop structure of LNA-m-HpDNA was unfolded after hybridization with target DNA, which forced biotin away from the electrode surface. Streptavidin-labeled horseradish peroxidase (Streptavidin-HRP) was subsequently immobilized on the electrode surface via the specific conjugation of biotin and streptavidin. Thereafter, the resulting HRP/target DNA–LNA-m-HpDNA (cDNA–LNA)/AuNPs modified Au electrode was successfully assembled for the construction of the DNA biosensor. Cyclic voltammetry and electrochemical impedance spectroscopy were carried out for the characterization of modified electrodes. Electrochemical reduction signal of benzoquinone was investigated in this work to indirectly analyze DNA hybridization via chronoamperometry. Under optimum conditions, the biosensor showed a good linear relationship between the current value and logarithm of the target DNA concentration ranging from 10 to 1000 pM with a low detection limit of 6.0 pM (S/N = 3). Furthermore, the DNA biosensor exhibited excellent discrimination ability to detect single-base mismatched DNA, three-base mismatched DNA and non-complementary DNA sequence. This strategy could provide a new platform for disease diagnose with high sensitivity.Highlights► Locked nucleic acid modified hairpin DNA was used for signal amplification. ► Enzymatic amplification technology was carried out in this experiment. ► The hybridization and discrimination of DNA were successfully investigated.
Co-reporter:Yunlei Zhou, Huanshun Yin, Xiaomeng Meng, Zhenning Xu, Yanrong Fu, Shiyun Ai
Electrochimica Acta 2012 Volume 71() pp:294-301
Publication Date(Web):1 June 2012
DOI:10.1016/j.electacta.2012.04.014
The direct electrochemistry of sacrosine oxidase (SOX) immobilized on graphene, chitosan and silver nanoparticles (AgNPs) modified glassy carbon electrode was realized. SOX exhibits a pair of well-defined reversible redox peaks in 0.1 M pH 7.0 phosphate buffer solution (PBS) with the oxidation peak potential of −0.446 V and the reduction peak potential of −0.496 V. The immobilized SOX retains its bioactivity, and exhibits a surface confined, reversible two-proton and two-electron transfer reaction. It also has good stability, and a fast heterogeneous electron transfer rate with the rate constant (ks) of 1.8 s−1. The surface coverage of SOX is 1.18 × 10−7 mol/cm2. This biosensor shows excellent sensitivity towards H2O2 in 0.1 M PBS (pH 7.0) with a wide linear range from 1.0 to 177 μM. The detection limit is 1.0 μM. The apparent Michaelis–Menten constant for immobilized SOX is calculated to be 0.18 mM. The excellent performance of the biosensor is attributed to large specific surface area and high conductivity of graphene and AgNPs, and good biocompatibility of chitosan, which improve the enzyme absorption and promote direct electron transfer between SOX and the electrode surface.Highlights► Sarcosine oxidase electrochemical biosensor was fabricated. ► The electrode was based on graphene, chitosan and silver nanoparticles. ► The direct electrochemistry of sarcosine oxidase was realized. ► The fabricated biosensor showed catalytic activity towards H2O2 determination.
Co-reporter:Lin Cui, Lijian Chen, Minrong Xu, Haichao Su, Shiyun Ai
Analytica Chimica Acta 2012 Volume 712() pp:64-71
Publication Date(Web):27 January 2012
DOI:10.1016/j.aca.2011.11.021
An enzyme-free amperometric method was established for the electrochemical reduction tert-butyl hydroperoxide (TBHP) on the utilization of nano-cobalt phthalocyanine (CoPc) loaded functionalized graphene (FGR) and to create a highly responsive organic peroxide sensor. FGR was synthesized with a simple and fast method of electrolysis with potassium hexafluorophosphate (KPF6) solution as electrolyte under the static current of 0.2 A. In the present work, FGR was dispersed in the solution of CoPc to fabricate chemical modified electrode to detect TBHP. The electro-reduction of TBHP can be catalyzed by FGR–CoPc, which has an excellent electrocatalytical activity due to the synergistic effect of the FGR with CoPc. The sensor can be applied to the quantification of TBHP with a linear range covering from 0.0260 to 4.81 mM, a high sensitivity of 13.64 A M−1, and a low detection limit of 5 μM. This proposed sensor was designed as a simple, robust, and cheap analytical device for the determination of TBHP in body lotion.Graphical abstractHighlights► A sensor fabricated on cobalt phthalocyanine loaded functionalized graphene. ► The sensor can be applied to the tert-butyl hydroperoxide (TBHP) reduction. ► This proposed sensor was designed to detection TBHP in body lotion.
Co-reporter:Huanshun Yin, Yunlei Zhou, Chuanxia Chen, Lusheng Zhu and Shiyun Ai
Analyst 2012 vol. 137(Issue 6) pp:1389-1395
Publication Date(Web):07 Feb 2012
DOI:10.1039/C2AN16098F
The abnormal expression of microRNAs (miRNAs) in many solid tumors makes miRNAs potential biomarkers for disease diagnosis and highlights the need for the sensitive and selective detection of miRNAs. In the present work, an ‘off-on’ signaling genosensor platform for miRNA-21 detection was well developed. This tactic was based on a locked nucleic acid-integrated nucleic acid hairpin probe, a biotin-labeled bridge DNA–AuNPs–bio-barcode signal amplification unit and enzymatic signal amplification. The test is simple, fast and ultrasensitive with a linear range of 0.01–700 pM. The detection limit was estimated to be 6 fM. The overexpression of miRNA-21 was confirmed in total RNA extracted from human hepatocarcinoma cells BEL-7402 and human HeLa cells compared with the control sample extracted from normal human hepatic L02 cells. This method does not need miRNA-21 labeling, isolation, enrichment or PCR amplification. The performance of the assay developed here could satisfy the need for rapid, easy, sensitive and specific early cancer diagnosis in clinical diagnostics.
Co-reporter:Yunlei Zhou, Zhaoyan Zhang, Zhenning Xu, Huanshun Yin and Shiyun Ai
New Journal of Chemistry 2012 vol. 36(Issue 10) pp:1985-1991
Publication Date(Web):05 Jul 2012
DOI:10.1039/C2NJ40253J
A sensitive and selective electrochemical method for microRNA-21 (miRNA-21) detection was developed. This detection tactic was based on graphene, gold nanoparticles (AuNPs), locked nucleic acid (LNA) incorporated hairpin DNA switching and enzymatic signal amplification. Graphene and AuNPs can improve the electrode conductivity and increase the electrode active surface. The LNA incorporated hairpin DNA probe was modified with biotin at its 5′-end and –SH at its 3′-end. After the probe hybridized with target miRNA-21, its loop-and-stem structure was unfolded to force the biotin away from the electrode surface. Through the specific interaction between biotin and streptavidin-horseradish peroxidase (streptavidin-HRP), miRNA-21 can be quantitatively realized by electrochemical detection of the enzymatic product of benzoquinone in the presence of hydrogen peroxide and hydroquinone. The determination conditions, such as probe concentration, probe immobilization time, hybridization time and applied potential, were optimized. This assay allowed the detection of miRNA-21 in the range of 1–5000 pM with a detection limit of 0.4 pM (S/N = 3). Based on the locked nucleic acid incorporated probe with hairpin structure, the sensor can well discriminated complementary and base mismatched sequences. Successful attempts were made in miRNA-21 expression analysis of human HeLa cells and normal human hepatic L02 cells.
Co-reporter:Xiaomeng Meng, Zhenning Xu, Mo Wang, Huanshun Yin and Shiyun Ai
Analytical Methods 2012 vol. 4(Issue 6) pp:1736-1741
Publication Date(Web):30 Mar 2012
DOI:10.1039/C2AY00007E
A simple electrochemical method based on a Bi2S3 modified glassy carbon electrode (GCE) was developed to determine antipyrine using cyclic voltammetry and differential pulse voltammetry. Antipyrine shows a well-defined oxidation peak at the fabricated electrode in phosphate buffer solution and the oxidation peak current is much higher than that at the bare GCE, indicating that Bi2S3 can effectively improve the oxidation of antipyrine. Several effect factors on antipyrine determination were optimized, such as Bi2S3 amount, solution pH, scan rate and accumulation time. Under the optimal conditions, the oxidation peak current of antipyrine was proportional to its concentration in the range of 2.0 to 100 μM and 100 to 800 μM with a correlation coefficient of 0.9974 and 0.9956, respectively. The limit of detection was estimated to be 0.7 μM (S/N = 3). The developed method showed good reproducibility and excellent anti-interference performance. The fabricated electrode was successfully used to determine antipyrine in pharmaceutical formulations with recovery from 96% to 103.5%.
Co-reporter:Haichao Su, Bing Sun, Lijian Chen, Zhenning Xu and Shiyun Ai
Analytical Methods 2012 vol. 4(Issue 12) pp:3981-3986
Publication Date(Web):28 Sep 2012
DOI:10.1039/C2AY25794G
A facile, economic and eco-friendly colorimetric detection method for dopamine has been well-established in this paper. It is based on the interaction between Cu2+ ions with amino group and hydroxyl groups of the dopamine adsorbed on the surface of gold nanoparticles (GNPs). Cu2+ ions serve as the selective “discriminator and linker” for dopamine detection. At high ionic strength, introduction of Cu2+ ions to GNPs solution including dopamine arouses the aggregation of GNPs, the color of the solution changes from wine red to blue, and the red shift of ultraviolet absorption peaks. The concentration of dopamine can be determined by monitoring with the naked eye or a UV-vis spectrometer. The calibration curve showed that the absorption ratio value at 650 and 525 nm (A650/A525) increased linearly over the dopamine concentration range of 5 × 10−7 M to 1 × 10−5 M with a limit of detection of 2 × 10−7 M (3σ). This method exhibits excellent selectivity for dopamine over other α-amino acids, glutathione, glucose, uric acid and ascorbic acid, and the process of the experiment, including the preparation of GNPs, detection of dopamine, pretreatment of sample, is finished within 30 min at room temperature. On the other hand, this probe was successfully applied to detect dopamine in human serum with high sensitivity, and this strategy may provide a selective sensing approach for measuring dopamine under physiological conditions.
Co-reporter:Huanshun Yin, Xiaomeng Meng, Zhenning Xu, Lijian Chen and Shiyun Ai
Analytical Methods 2012 vol. 4(Issue 5) pp:1445-1451
Publication Date(Web):21 Mar 2012
DOI:10.1039/C2AY05912F
A selective and sensitive electrochemistry method was developed for the determination of phenacetin on CdSe microspheres modified glassy carbon electrode (GCE). The electrode exhibited an effectively catalytic response to the oxidation of phenacetin, which was testified by the increased oxidation peak current and the decreased oxidation peak potential compared with the bare GCE. The scan rate investigation demonstrated that the electrochemical oxidation was an adsorption-controlled process in the range from 20 to 500 mV s−1. Under optimal determination conditions, the oxidation peak current of phenacetin was proportional to its concentration in the range of 0.5 to 800 μM. The limit of detection was estimated to be 0.1 μM (S/N = 3). The developed method showed good reproducibility, acceptable stability and excellent anti-interference performance. The fabricated electrode was successfully used to determine phenacetin in pharmaceutical formulation samples.
Co-reporter:Haichao Su, Lijian Chen, Bing Sun, Shiyun Ai
Sensors and Actuators B: Chemical 2012 174() pp: 458-464
Publication Date(Web):
DOI:10.1016/j.snb.2012.08.080
Co-reporter:Lin Cui, Jianying Zhu, Xiaomeng Meng, Huanshun Yin, Xiaoping Pan, Shiyun Ai
Sensors and Actuators B: Chemical 2012 Volume 161(Issue 1) pp:641-647
Publication Date(Web):3 January 2012
DOI:10.1016/j.snb.2011.10.083
The graphene nanosheets and carbon nanospheres mixture (GNS–CNS) was prepared by electrolyzing graphite rob in KNO3 solution under a constant current. The cationic chitosan (CS) coated Prussian blue (PB) as an efficient redox mediator could interact with the anion GNS–CNS via electrostatic interaction. The synergy effect of CS@PB nanoparticles and GNS–CNS contributed to the excellent electrochemical response towards the nitrite oxidation. The as-prepared CS@PB/GNS–CNS modified glass carbon (GC) electrode demonstrated its high sensitivity, low detection limit, short response time, and wide concentration range for the nitrite detection.
Co-reporter:Haichao Su, Qiang Ma, Kun Shang, Tao Liu, Huanshun Yin, Shiyun Ai
Sensors and Actuators B: Chemical 2012 Volume 161(Issue 1) pp:298-303
Publication Date(Web):3 January 2012
DOI:10.1016/j.snb.2011.10.035
A novel and sensitive colorimetric method for assay of Escherichia coli O157:H7 was developed as a model for Gram-negative bacteria by a mercaptoethylamine-modified gold nanoparticles (MEA-AuNPs) sensor. Mercaptoethylamine (MEA) molecule binded with E. coli O157:H7 via electrostatic adhesion between the positive electricity of MEA and the negative electricity of E. coli O157:H7. Furthermore MEA can be easily conjugated to AuNPs through –SH group. Thus, the MEA-AuNPs can be cross linked in the presence of certain amount of E. coli O157:H7, resulting in a dramatic color change from red to blue. It is worth noting that the absorption ratio (A625/A520) of the modified AuNPs exhibited a linear correlation with E. coli O157:H7 concentration. Therefore, the concentration of E. coli O157:H7 can be detected by the naked eyes. This bioassay is rapid, takes less than 5 min from bacterium binding to detection and analysis, and is also convenient. Therefore, MEA-AuNPs system as a novel, on-site, real-time and low-cost Gram-negative bacteria sensor, would have a wide range of practical applications.
Co-reporter:Huanshun Yin, Yunlei Zhou, Haixia Zhang, Xiaomeng Meng, Shiyun Ai
Biosensors and Bioelectronics 2012 Volume 33(Issue 1) pp:247-253
Publication Date(Web):15 March 2012
DOI:10.1016/j.bios.2012.01.014
MicroRNAs (miRNAs), a kind of small, endogenous, noncoding RNAs (∼22 nucleotides), might play a crucial role in early cancer diagnose due to its abnormal expression in many solid tumors. As a result, label-free and PCR-amplification-free assay for miRNAs is of great significance. In this work, a highly sensitive biosensor for sequence specific miRNA-21 detection without miRNA-21 labeling and enrichment was constructed based on the substrate electrode of dendritic gold nanostructure (DenAu) and graphene nanosheets modified glassy carbon electrode. Sulfydryl functionalized locked nucleic acid (LNA) integrated hairpin molecule beacon (MB) probe was used as miRNA-21 capture probe. After hybridized with miRNA-21 and reported DNA loading in gold nanoparticles (AuNPs) and biotin multi-functionalized bio bar codes, streptavidin–HRP was brought to the electrode through the specific interaction with biotin to catalyze the chemical oxidation of hydroquinone by H2O2 to form benzoquinone. The electrochemical reduction signal of benzoquinone was utilized to monitor the miRNA-21 hybridization event. The effect of experimental variables on the amperometric response was investigated and optimized. Based on the specific confirmation of probe and signal amplification, the biosensor showed excellent selectivity and high sensitivity with low detection limit of 0.06 pM. Successful attempts are made in miRNA-21 expression analysis of human hepatocarcinoma BEL-7402 cells and normal human hepatic L02 cells.Graphical abstractHighlights► A sensitive biosensor for sequence specific miRNA detection was developed. ► This detection method does not need miRNA labeling and enrichment. ► The sensor showed high selectivity and sensitivity.
Co-reporter:Jing Dong;Tao Liu;Xiaomeng Meng;Jianying Zhu
Journal of Solid State Electrochemistry 2012 Volume 16( Issue 12) pp:3783-3790
Publication Date(Web):2012 December
DOI:10.1007/s10008-012-1812-6
A new method based on specific binding between glycoprotein acetylcholinesterase and boronic acid-functionalized Fe@Au magnetic nanoparticles was presented for the development of acetylcholinesterase biosensor. Alginate–graphene composite-modified electrode was firstly prepared as the substrate. Then, biocompatible boronic acid-functionalized Fe@Au magnetic nanoparticles were anchored by the covalence between the cis-diol of alginate and the boronic acid group on Fe@Au nanoparticles. Acetylcholinesterase was subsequently immobilized via the bonding between the glycosyl of acetylcholinesterase and the boronic acid group. The immobilized enzyme retained relatively high bioactivity and the fabricated biosensor exhibited high sensitivity and fast response to acetylthiocholine chloride. Based on enzyme inhibition, carbamate pesticide was detected using Furadan as a model compound. Two linear ranges of 0.05–15 and 15–400 ppb were obtained with a detection limit of 0.01 ppb. The biosensor also showed acceptable reproducibility and relatively good storage stability. Moreover, satisfactory results were obtained in the real sample analysis.
Co-reporter:Ruixia Han;Lin Cui;Shiyun Ai;Huanshun Yin
Journal of Solid State Electrochemistry 2012 Volume 16( Issue 2) pp:449-456
Publication Date(Web):2012/02/01
DOI:10.1007/s10008-011-1352-5
A tyrosinase (Tyr) biosensor has been constructed by immobilizing tyrosinase on the surface of Mg–Al–CO3 hydrotalcite-like compound film (HTLc) modified glassy carbon electrode (GCE) for the determination of polyphenols. The negatively charged tyrosinase was adsorbed firmly on the surface of a positively charged HTLc/GCE by electrostatic interactions and retained its activity to a great degree. The modified electrode was characterized by cyclic voltammetry and AC impedance spectra. Polyphenols were determined by a direct reduction of biocatalytically generated quinone species. The different parameters, including pH, temperature, and enzyme loading were investigated and optimized. Under the optimum conditions, Tyr/HTLc electrode gave a linear response range of 3–300, 0.888–444, and 0.066–396 μM with a detection limit (S/N = 3) of 0.1, 0.05, and 0.003 μM for catechol, caffeic acid, and quercetin, respectively. In addition, the repeatability and stability of the enzyme electrode were estimated. Total polyphenol contents of real samples were also determined to study the potential applicability of the Tyr/HTLc/GCE biosensor.
Co-reporter:Huanshun Yin;Yunlei Zhou;Ruixia Han
Journal of Solid State Electrochemistry 2012 Volume 16( Issue 1) pp:75-82
Publication Date(Web):2012 January
DOI:10.1007/s10008-010-1280-9
Hydroxylapatite (HAP)-modified glassy carbon electrode (GCE) was fabricated and used to investigate the electrochemical oxidation behavior of 2,4-dinitrophenol (2,4-DNP) by cyclic voltammetry, differential pulse voltammetry, and chronocoulometry. The oxidation peak current of 2,4-DNP at the modified electrode was obviously increased compared with the bare GCE, indicating that HAP exhibits a remarkable enhancement effect on the electrochemical oxidation of 2,4-DNP. Based on this, a sensitive and simple electrochemical method was proposed for the determination of 2,4-DNP. The effects of HAP concentration, accumulation time, accumulation potential, pH, and scan rate were examined. Under optimal conditions, the oxidation peak current of 2,4-DNP was proportional to its concentration in the range from 2.0 × 10−6 to 6.0 × 10−4 M with a correlation coefficient of 0.9987. The detection limit was 7.5 × 10−7 M (S/N = 3). The proposed method was further applied to determine 2,4-DNP in water samples with recoveries from 96.75% to 106.50%.
Co-reporter:Kun Shang, Jianying Zhu, Xiaomeng Meng, Ziqiang Cheng, Shiyun Ai
Biosensors and Bioelectronics 2012 Volume 37(Issue 1) pp:107-111
Publication Date(Web):August–September 2012
DOI:10.1016/j.bios.2012.04.035
A novel electrochemical immunosensor for ultrasensitive detection of subgroup J of avian leukosis virus (ALVs-J) was designed by using graphene sheets (GS)-layered double hydroxides (LDHs) composites modified electrode with multifunctional Fe3O4 core/Ni–Al LDHs shell (LDHs@Fe3O4) nanospheres as labels. At first, the GS-LDHs were used for the immunosensor platform for improving the electronic transmission rate as well as increasing the surface area to capture a large amount of primary antibodies (Ab1). After that, ferrocene (Fc), secondary antibodies (Ab2) and horseradish peroxidase (HRP) multifunctional LDHs@Fe3O4 nanospheres were used as labels with high load amount and good biological activity. Subsequently, in presence of H2O2, amplified signals were obtained by an electrochemical sandwich immunoassay protocol. To embody the signal amplification property of the protocol, the analytical properties of various immunosensor platform and labels were compared in detail. Under optimal conditions, the reduction peak currents of the electrochemical immunosensor were proportional to the ALVs-J concentration over the range from 102.32 to 105.50 TCID50/mL with a low detection limit (180 TCID50/mL, S/N=3). The resulting immunosensor also displayed a good selectivity, reproducibility and stability.Graphical abstractHighlights► Fe3O4 core/Ni–Al layered double hydroxides shell nanospheres were used as labels. ► Graphene sheets-layered double hydroxides composites were used for the immunosensor platform. ► Subgroup J of avian leukosis virus were detected by ultrasensitive electrochemical immunnoassay technology. ► The extreme enhancement of the sensitivity was partly due to the cooperation effect of LDHs and HRP.
Co-reporter:Huanshun Yin, Qingming Zhang, Yunlei Zhou, Qiang Ma, Tao liu, Lusheng Zhu, Shiyun Ai
Electrochimica Acta 2011 Volume 56(Issue 6) pp:2748-2753
Publication Date(Web):15 February 2011
DOI:10.1016/j.electacta.2010.12.060
Graphene–chitosan composite film modified glassy carbon electrode was prepared and characterized. The fabricated electrode showed excellent electrochemical catalytic activities towards the oxidation of catechol (CT), resorcinol (RS) and hydroquinone (HQ). The oxidation overpotentials of CT, RS and HQ decreased significantly and the corresponding oxidation currents increased remarkably compared with those obtained at the bare GCE and chitosan modified GCE. Some kinetic parameters, such as the electron transfer number (n), proton transfer number (m), charge transfer coefficient (α) and the apparent heterogeneous electron transfer rate constant (ks), were calculated. Differential pulse voltammetry was used for the simultaneous determination of CT, RS and HQ in their ternary mixture. The peak-to-peak potential separations between CT and RS, RS and HQ, and HQ and CT were 0.388, 0.484 and 0.096 V, respectively. The calibration curves for CT, RS and HQ were obtained in the range of 1 × 10−6 to 4 × 10−4, 1 × 10−6 to 5.5 × 10−4 and 1 × 10−6 to 3 × 10−4 mol L−1, respectively. The detection limits were 7.5 × 10−7 mol L−1 (S/N = 3).
Co-reporter:Qiang Ma, Tao Liu, Tiantian Tang, Huanshun Yin, Shiyun Ai
Electrochimica Acta 2011 Volume 56(Issue 24) pp:8278-8284
Publication Date(Web):1 October 2011
DOI:10.1016/j.electacta.2011.06.088
The electrochemical inactivation of microorganisms by a hemin/graphite felt (GF) composite electrode was investigated, and Escherichia coli was treated as the testing species. The composite electrode was constructed by chemically bonding hemin molecules onto an amino-mineralized GF (AGF) surface. Then, the electrode was characterized systematically by electrochemical methods, and the kinetic parameters of the modified electrode were investigated. The hemin molecules on the surface of the composite electrode have high activity for the reduction of O2. When the composite electrode was applied with negative potentials, the dissolved oxygen was electrochemically reduced to reactive oxygen species (ROS, such as H2O2 and OH) at the cathode surface. The ROS can cause biological damage and can eventually result in the death of bacteria. A sterilizing rate up to 99.9% could be obtained after 60 min of inactivation. Thus, this composite electrode could be applied to disinfect drinking water efficiently at a low potential (−0.6 V vs. SCE) without any addition of chloride.Highlights► A hemin/graphite felt composite electrode, bonding hemin molecules on to the amino mineralized graphite felt surface, was successfully used as working electrode for the electrochemical inactivation of E. coli. ► The main contribution to the bacteria inactivation process is the oxidation in the liquid bulk by in situ electrogenerated reactive oxygen species (ROS). ► The ROS demonstrated to be sufficient to perform an effective disinfection, without the mediation of active chlorine substance.
Co-reporter:Xianggang Liu, Ziqiang Cheng, Hai Fan, Shiyun Ai, Ruixia Han
Electrochimica Acta 2011 Volume 56(Issue 18) pp:6266-6270
Publication Date(Web):15 July 2011
DOI:10.1016/j.electacta.2011.05.055
A sensitive electrochemical method for the detection of avian influenza virus (AIV) H5N1 gene sequence using a DNA aptamer immobilized onto a hybrid nanomaterial-modified electrode was developed. To enhance the selectivity and sensitivity, the modified electrode was assembled with multi-wall carbon nanotubes (MWNT), polypyrrole nanowires (PPNWs) and gold nanoparticles (GNPs). This electrode offered a porous structure with a large effective surface area, highly electrocatalytic activities and electronic conductivity. Therefore, the amount of DNA aptamer immobilized onto the electrode was increased while the accessibility of the detection target was maintained. The biosensor is based on the hybridization and preferred orientation of a DNA aptamer immobilized onto a modified electrode surface with its target (H5N1 specific sequence) present in solution. It is selective for the H5N1 specific sequence, and the signal of the indicator was approximately linear to log(concentration) of the H5N1 specific sequence from 5.0 × 10−12 to 1.0 × 10−9 M (R = 0.9863) with a detection limit of 4.3 × 10−13 M. These studies showed that the new hybrid nanomaterial (MWNT/PPNWs/GNPs) and the DNA aptamer could be used to fabricate an electrochemical biosensor for gene sequence detection. Furthermore, this design strategy is expected to have extensive applications in other biosensors.Highlights► A sensitive electrochemical biosensor for the detection of gene sequence was developed. ► The biosensor was assembled by MWNT, polypyrrole nanowires and gold nanoparticles. ► The hybrid nanomaterials could provide a porous structure with good properties. ► The biosensor has highly selectivity and sensitivity. ► The design strategy is expected to have extensive applications in other biosensors
Co-reporter:Lin Cui, Xiaomeng Meng, Minrong Xu, Kun Shang, Shiyun Ai, Yinping Liu
Electrochimica Acta 2011 Volume 56(Issue 27) pp:9769-9774
Publication Date(Web):30 November 2011
DOI:10.1016/j.electacta.2011.08.026
In this paper, a novel nitrite sensor was constructed based on electrodeposition of gold nanoparticles (AuNPs) on a copper calcined layered double hydroxide (Cu-CLDH) modified glassy carbon electrode. Electrochemical experiments showed that AuNPs/CLDH composite film exhibited excellent electrocatalytic oxidation activity with nitrite due to the synergistic effect of the Cu-CLDH with AuNPs. The fabricated sensor exhibited excellent performance for nitrite detection within a wide concentration interval of 1–191 μM and with a detection limit of 0.5 μM. The superior electrocatalytic response to nitrite was mainly attributed to the large surface area, minimized diffusion resistance, and enhanced electron transfer of the Cu-CLDH and AuNPs composition film. This platform offers a novel route for nitrite sensing with wide analytical applications and will supply the practical applications for a variety of simple, robust, and easy-to-manufacture analytical approaches in the future.Highlights► A nitrite sensor fabricated based on copper calcined layered double hydroxides and gold nanoparticles modified electrode. ► This sensor exhibited excellent electrocatalytic oxidation to nitrite. ► This nitrite sensor exhibited very good analytical performance with low cost, convenient preparation and rapid detection.
Co-reporter:Huanshun Yin, Lin Cui, Quanpeng Chen, Weijie Shi, Shiyun Ai, Lusheng Zhu, Linan Lu
Food Chemistry 2011 Volume 125(Issue 3) pp:1097-1103
Publication Date(Web):1 April 2011
DOI:10.1016/j.foodchem.2010.09.098
A simply and sensitively electroanalytical method for determination of bisphenol A (BPA) using poly(amidoamine) (PAMAM) and Fe3O4 magnetic nanoparticles modified glassy carbon electrode (GCE) was presented. Compared with bare electrode, PAMAM–Fe3O4 modified electrode not only significantly enhanced the oxidation peak current of BPA, but also lowered the oxidation overpotential, suggesting that the modified electrode can remarkably improve the determining sensitivity of BPA. Factors influencing the detection processes were optimised and kinetic parameters were calculated. Under the optimal conditions, the oxidation current increased linearly with increasing the concentration of BPA in the range of 1 × 10−8–3.07 × 10−6 M with the correlation coefficient of 0.9996 and the detection limit of 5 × 10−9 M. The current reached 95% of the steady-state current within about 6 s. The proposed method was successfully applied to determine BPA in milk samples and satisfactory results were obtained.
Co-reporter:Peng Ju, Hai Fan, Tao Liu, Lin Cui, Shiyun Ai
Journal of Luminescence 2011 Volume 131(Issue 8) pp:1724-1730
Publication Date(Web):August 2011
DOI:10.1016/j.jlumin.2011.03.070
The interaction between flower-like CdSe nanostructure particles (CdSe NP) and bovine serum albumin (BSA) was investigated from a spectroscopic angle under simulative physiological conditions. Under pH 7.4, CdSe NP could effectively quench the intrinsic fluorescence of BSA via static quenching. The binding constant (KA) was 6.38, 3.27, and 1.90×104 M−1 at 298, 304, and 310 K, respectively and the number of binding sites was 1.20. According to the Van't Hoff equation, the thermodynamic parameters (ΔH°=−77.48 kJ mol−1, ΔS°=−168.17 J mol−1 K−1) indicated that hydrogen bonds and van der Waals forces played a major role in stabilizing the BSA−CdSe complex. Besides, UV–vis and circular dichroism (CD) results showed that the addition of CdSe NP changed the secondary structure of BSA and led to a decrease in α-helix. These results suggested that BSA underwent substantial conformational changes induced by flower-like CdSe nanostructure particles.Highlights► Estimate the binding of flower-like CdSe NP to BSA by spectroscopic methods. ► Hydrogen bonds and van der Waals forces were the major forces. ►Addition of CdSe changed the micro-environmentl of BSA. ► Decrease in α-helix of BSA secondary structure induced by CdSe.
Co-reporter:Jun Wang, Huanshun Yin, Xiaomeng Meng, Jianying Zhu, Shiyun Ai
Journal of Electroanalytical Chemistry 2011 Volume 662(Issue 2) pp:317-321
Publication Date(Web):15 November 2011
DOI:10.1016/j.jelechem.2011.08.019
In this work, a mixture of carbon materials was prepared by simple and fast method based on electrolyzing graphite rod in KNO3 solution under the constant current. The transmission electron microscope (TEM) indicated that the mixture was comprised of graphene nanosheets and carbon nanoparticles, and some carbon nanoaprticles were adsorbed on the surface of graphene nanosheet. The mixture modified glassy carbon electrode showed excellent catalytic and adsorptive ability towards the redox of hydroquinone (HQ). The effect factors, such as pH, scan rate, accumulation time and accumulation potential, were optimized. The chronocoulometry investigation demonstrated that the mixture can effectively increase the electrochemical active surface. Under the optimal determination conditions, the oxidation peak current was proportional to HQ concentration in the range of 0.1–100 and 100–600 μM. The detection limit was estimated to be 0.01 μM (S/N = 3). The developed electrode was further applied to determine HQ in soil samples with satisfactory results.Graphical abstractHighlights► The graphene nanosheets and carbon nanospheres mixture was prepared. ► The prepared mixture modified glassy carbon electrode was fabricated. ► The fabricated electrode showed excellent catalytic ability towards hydroquinone. ► The prepared mixture can increase the electrochemical active area of electrode. ► The developed method can determine HQ in soil samples with satisfactory results.
Co-reporter:Xianggang Liu, Yinghua Peng, Xiangjin Qu, Shiyun Ai, Ruixia Han, Xiangbin Zhu
Journal of Electroanalytical Chemistry 2011 Volume 654(1–2) pp:72-78
Publication Date(Web):1 May 2011
DOI:10.1016/j.jelechem.2011.01.024
A novel bio-composite film which contains multi-walled carbon nanotube (MWNT)-chitosan (Chit)/poly(amidoamine) (PAMAM) nanocomposite along with the incorporation of DNA modified Au electrode as a biosensor for determination of dopamine(DA) and uric acid (UA) under coexistence of ascorbic acid (AA) was fabricated by layer-by-layer modification. Electrochemical impedance spectroscopy (EIS) and Cyclic Voltametry (CV) were used to characterize the electrochemical properties of the modified electrodes. The biosensor was applied to detect DA and UA in the presence of AA. It not only exhibited strong catalytic activity toward the oxidation of DA and UA but also separated the originally overlapped signals of UA, DA and AA oxidation at the bare electrode into three well-defined peaks. The peak separation between AA and DA, AA and UA was 179 mV and 288 mV, respectively. In the presence of 1.0 mM AA, two linear relationships were obtained for DA over the concentration range from 0.2 to 10 μM (R = 0.9984) and 10–100 μM (R = 0.9957) with a detection limit of 0.03 μM (s/n = 3). The anodic peak current of UA was also a linear relationship in the concentration range 0.5–100 μM (R = 0.9971) with a detection limit of 0.07 μΜ. Moreover, the modified electrode surface has very good reproducibility and stability.Research highlights► A nanocomposite of MWNT-Chit/PAMAM/DNA modified Au electrode was fabricated. ► It was applied to detect DA and UA in the presence of AA. ► It exhibited strong catalytic activity toward the oxidation of DA and UA. ► It was highly sensitive with detection limit of 0.03 μM DA and 0.07 μM UA. ► It surface reproducibility was satisfactory, and it has a long-term stability.
Co-reporter:Tao Liu, Xiangbin Zhu, Lin Cui, Peng Ju, Xiangjin Qu, Shiyun Ai
Journal of Electroanalytical Chemistry 2011 Volume 651(Issue 2) pp:216-221
Publication Date(Web):1 February 2011
DOI:10.1016/j.jelechem.2010.11.026
A novel and reliable electrochemical sensor based on PbO2-carbon nanotubes-room temperature ionic liquid (i.e., 1-butyl-3-methylimidazolium hexafluorophosphate, BMIMPF6) composite film modified glassy carbon electrode (GCE) (PbO2–MWNT–RTIL/GCE) was proposed for simultaneous and individual determination of guanine and adenine. The guanine and adenine oxidation responses were monitored by differential pulse voltammetric (DPV) measurement. Compared with the bare electrode, the PbO2–MWNT–RTIL/GCE not only significantly enhanced the oxidation peak currents of guanine and adenine, but also lowered their oxidation overpotentials, suggesting that the synergistic effect of PbO2, MWNT and RTIL could dramatically improve the determining sensitivity of guanine and adenine. The PbO2–MWNT–RTIL/GCE showed good stability, high accumulation efficiency and enhanced electrocatalytic ability for the detection of guanine and adenine. Besides, the modified electrode also exhibited good behaviors in the simultaneous detection of adenine and guanine with the peak separation of 0.29 V in 0.1 M pH 7.0 phosphate buffer solution (PBS). Under the optimal conditions, the detection limit for individual determination of guanine and adenine was 6.0 × 10−9 M and 3.0 × 10−8 M (S/N = 3), respectively. The proposed method for the measurements of guanine and adenine in herring sperm DNA was successfully applied with satisfactory results.
Co-reporter:Lin Cui;Huanshun Yin;Shiyun Ai;Lifang Li
Chinese Journal of Chemistry 2011 Volume 29( Issue 4) pp:829-834
Publication Date(Web):
DOI:10.1002/cjoc.201190165
Abstract
The electrocatalysis oxidation of guanosine-5′-monophosphate (GMP) was investigated on Mg-Al layered double hydroxide (LDH) functionalized with sodium dodecyl sulfate (SDS) and room temperature ionic liquid (RTIL) modified glass carbon electrode (GCE). The cyclic voltammogram of GMP on the modified electrode (RTIL/ LDH-SDS/GCE) exhibited a well defined anodic peak at 1.091 V in 0.2 mol·L−1 pH 4.4 acetate buffer solution. The GMP oxidation was enhanced in the presence of anionic surfactant in the ?lms. The results suggest that the surfactant molecules intercalate the LDH layers to preconcentrate GMP molecules and the RTIL showed good ionic conductivity. The experimental parameters were optimized, the kinetic parameters were investigated and the probable oxidation mechanism was proposed. Under the optimized conditions, the oxidation peak current was proportional to GMP concentration in the range from 5.0×10−7 to 1.0×10−4 mol·L−1 with the correlation coefficient of 0.9987 and the detection limit was 1.0×10−7 mol·L−1. The RTIL/LDH-SDS/GCE showed a good electrochemical response to the oxidation of GMP and would be developed into a new biosensor.
Co-reporter:Lin Cui, Minrong Xu, Jianying Zhu, Shiyun Ai
Synthetic Metals 2011 Volume 161(15–16) pp:1686-1690
Publication Date(Web):August 2011
DOI:10.1016/j.synthmet.2011.06.004
In the present work, we have developed a novel hydrogen peroxide (H2O2) biosensor based on electropolymerization of thiophene-3-boronic acid film (TBA) in ionic liquid via glucosidic bond with glycoprotein horseradish peroxidase (HRP). A thin film of poly (thiophene-3-boronic acid) (PTBA) has been synthesized by electropolymerization using room temperature ionic liquids (RTIL) as the growth medium and the supporting electrolyte. Horseradish peroxidase (HRP) in this study shows affinity interaction with the formed PTBA thin film. With the aid of hydroquinone (H2Q) mediator, the biosensor has a fast response of less than 7 s with linear range of 5.0 × 10−6 to 1.75 × 10−4 M and a detection limit of 0.5 μM. The developed biosensor exhibits fast response, a low detection limit, high stability and very good reproducibility.Highlights► Electropolymerization of thiophene-3-boronic acid film in ionic liquid. ► Preparation a H2O2 biosensor via glycosidic bond to immobilize glycoprotein. ► This H2O2 biosensor displayed fast response, high sensitivity and good stability.
Co-reporter:Lin Cui, Huanshun Yin, Jing Dong, Hai Fan, Tao Liu, Peng Ju, Shiyun Ai
Biosensors and Bioelectronics 2011 Volume 26(Issue 7) pp:3278-3283
Publication Date(Web):15 March 2011
DOI:10.1016/j.bios.2010.12.043
An enzymeless biosensor was explored from Cu–Mg–Al calcined layered double hydroxide (CLDH) modified electrode in this study. The Cu–Mg–Al CLDH greatly promotes the electron transfer between H2O2 and GCE, and it is exemplified toward the non-enzymatic sensing of H2O2. The results indicate that the Cu–Mg–Al CLDH exhibits excellent electrocatalytic property, high sensitivity, good reproducibility, long-term stability, and fast amperometric response toward reduction of H2O2, thus is promising for the future development of man-made mimics of enzyme in H2O2 sensors. This work opens a way to utilize simply Cu–Mg–Al CLDH as an electron mediator to fabricate an efficient H2O2 biosensor, which exhibits great potential applications in varieties of simple, robust, and easy-to-make analytical approaches in the future.
Co-reporter:Huanshun Yin;Yunlei Zhou;Lin Cui
Journal of Solid State Electrochemistry 2011 Volume 15( Issue 1) pp:167-173
Publication Date(Web):2011 January
DOI:10.1007/s10008-010-1089-6
Electrochemical behavior of bisphenol A (BPA) at glassy carbon electrode-modified with layered double hydroxide (LDH) and anionic surfactant (sodium dodecyl sulfate) is investigated by electrochemical techniques. Compared with the bare electrode and LDH-modified electrode, the oxidation peak potential of BPA shifted negatively and the peak current increased significantly due to the enhanced accumulation of BPA via electrostatic interaction with LDH at the hydrophobic electrode surface. Some determination conditions such as LDH loading, pH, scan rate, accumulation potential, and accumulation time on the oxidation of BPA were optimized. And some kinetic parameters were investigated. Under the optimized conditions, the oxidation current was proportional to BPA concentration in the range of 8 × 10−9 to 2.808 × 10−6 M with the detection limit of 2.0 × 10−9 M by amperometry. The fabricated electrode showed good reproducibility, stability, and anti-interference. The proposed method was successfully applied to determine BPA in water samples, and the results were satisfactory.
Co-reporter:Huanshun Yin;Yunlei Zhou;Lin Cui;Tao Liu;Peng Ju;Lusheng Zhu
Microchimica Acta 2011 Volume 173( Issue 3-4) pp:337-345
Publication Date(Web):2011 June
DOI:10.1007/s00604-011-0568-5
The electrochemical behavior of rutin was investigated in pH 6.0 buffer solution using a glassy carbon electrode coated with graphene nanosheets, chitosan and a poly (amidoamine) dendrimer in pH 6.0 buffer solution. The results indicate that the modified electrode displays electrochemical redox activity towards rutin, and that the oxidation peak current of rutin increases significantly compared to that at other electrodes. The amount of immobilized graphene and dendrimer, pH value, scan rate, accumulation time and accumulation potential were optimized. The kinetic parameters, charge transfer coefficient, transfer electron number, proton transfer number, standard rate constant, were calculated. Under the optimized conditions, the oxidation peak current is proportional to the concentration of rutin in the range between 0.001 and 2.0 μmol L−1 (R = 0.9991). The detection limit is 0.6 nmol L−1 (at S/N = 3). The electrode exhibits satisfactory selectivity and reproducibility and was applied to the determination of rutin in pharmaceutical preparations, spiked human serum, and traditional Chinese medicine, with recoveries between 97.2 and 104.67%.
Co-reporter:Huanshun Yin;Yunlei Zhou;Qiang Ma;Tao Liu;Shiyun Ai;Lusheng Zhu
Microchimica Acta 2011 Volume 172( Issue 3-4) pp:343-349
Publication Date(Web):2011 March
DOI:10.1007/s00604-010-0499-6
The electrochemical oxidation of guanosine-5′-monophosphate (GMP) was studied with a glassy carbon electrode modified with a composite made from graphene and multi-walled carbon nanotubes. GMP undergoes an irreversible oxidation process at an oxidation peak potential of 987 mV in phosphate buffer solution. Compared to other electrodes, the oxidation peak current of GMP with this electrode was significantly increased, and the corresponding oxidation peak potential negatively shifted, thereby indicating that the modified material exhibited electrochemical catalytic activity towards GMP. Chronocoulometry demonstrates that the material also effectively increases the surface area of the electrode and increases the amount of GMP adsorbed. Under the optimum conditions, the oxidation current is proportional to the GMP concentration in the range from 0.1 to 59.7 μM with a correlation coefficient of 0.9991. The detection limit is 0.025 μM (at S/N = 3).
Co-reporter:Lin Cui;Shiyun Ai;Kun Shang;Xiaomeng Meng;Chengcheng Wang
Microchimica Acta 2011 Volume 174( Issue 1-2) pp:31-39
Publication Date(Web):2011 July
DOI:10.1007/s00604-011-0594-3
We have prepared a glassy carbon electrode modified with poly-2,6-pyridinedicarboxylic acid and with magnetic Fe3O4 nanoparticles. This modification enhances the effective surface area and the electrocatalytic oxidation of nicotinamide adenine dinucleotide (NADH) in addition to providing positively charged groups for electrostatic assembly of the phosphate group of NADH. The modified electrode responds linearly to NADH in the range from 5 × 10−8 to 2.5 × 10−5 M and gives a lower detection limit of 1 × 10−8 M. It displays satisfactory selectivity and reproducibility. The sensor was applied to rapid screening of plant extracts for their antioxidant properties.
Co-reporter:Tao Liu;Minrong Xu;Huanshun Yin;Shiyun Ai;Xiangjin Qu
Microchimica Acta 2011 Volume 175( Issue 1-2) pp:
Publication Date(Web):2011 October
DOI:10.1007/s00604-011-0665-5
An amperometric biosensor is described for the detection of organophosphorus pesticides. It is based on the enzyme tyrosinase immobilized on platinum nanoparticles and the use of a glassy carbon electrode modified with graphene. Tyrosinase was immobilized on the electrode surface via electrostatic interaction between a monolayer of cysteamine and the enzyme. In the presence of catechol as a substrate, the pesticides chlorpyrifos, profenofos and malathion can be determined as a result of their inhibition of the enzyme which catalyzes the oxidation of catechol to o-quinone. Platinum nanoparticles and graphene effectively enhance the efficiency of the electrochemical reduction of o-quinone, thus improving sensitivity. Under optimum experimental conditions, the inhibition effect of the pesticides investigated is proportional to their concentrations in the lower ppb-range. The detection limits are 0.2, 0.8 and 3 ppb for chlorpyrifos, profenofos and malathion, respectively. The biosensor displays good repeatability and acceptable stability.
Co-reporter:Huanshun Yin, Yunlei Zhou, Xiaomeng Meng, Kun Shang, Shiyun Ai
Biosensors and Bioelectronics 2011 30(1) pp: 112-117
Publication Date(Web):
DOI:10.1016/j.bios.2011.08.039
Co-reporter:Xianggang Liu, Xiangjin Qu, Jing Dong, Shiyun Ai, Ruixia Han
Biosensors and Bioelectronics 2011 Volume 26(Issue 8) pp:3679-3682
Publication Date(Web):15 April 2011
DOI:10.1016/j.bios.2011.01.034
A novel electrochemical method of detecting DNA hybridization is presented based on the change in flexibility between the single and double stranded DNA. A recognition surface based on gold nanoparticles (GNPs) is firstly modified via mixing self-assembled monolayer of thiolated probe DNA and 1,6-hexanedithiol. The hybridization and electrochemical detection are performed on the surface of probe-modified GNPs and electrode, respectively. Here in our method the charge transfer resistance (Rct) signal is enhanced by blocking the surface of electrode with DNA covered GNPs. The GNPs will be able to adsorb on the gold electrode when covered with flexible single stranded DNA (ssDNA). On the contrary, it will be repelled from the electrode, when covered with stiff double stranded DNA (dsDNA). Therefore, different Rct signals are observed before and after hybridization. The hybridization events are monitored by electrochemical impedance spectroscopy (EIS) measurement based on the Rct signals without any external labels. This method provides an alternative route for expanding the range of detection methods available for DNA hybridization.
Co-reporter:Haichao Su, Hai Fan, Shiyun Ai, Na Wu, Hongmin Fan, Pengcheng Bian, Jianchao Liu
Talanta 2011 Volume 85(Issue 3) pp:1338-1343
Publication Date(Web):15 September 2011
DOI:10.1016/j.talanta.2011.06.017
A novel and sensitive colorimetric method for determination of melamine in milk samples was developed by a 3-mercapto-1-propanesulfonate-modified gold nanoparticles (MPS-GNPs) probe. Melamine molecule has multiple –NH2 groups. These functional groups can interact with MPS to form strong hydrogen bonding and induce the aggregation of the MPS-GNPs, resulting in a dramatic color change from red to blue. Therefore, the concentration of melamine in milk samples can be quantitatively detected by the naked eyes or a UV-vis spectrometer. Moreover, investigations have revealed that the sensitivity of the detection could be clearly improved by adding NaCl to the modified GNPs solution, which leads to a more rapid color change in the NaCl-optimized GNPs system. It is worth noting that the absorption ratio (A650/A520) of the modified GNPs in the NaCl-optimized system exhibited a linear correlation with melamine concentration and the limit of detection is 8 nM, well below the safety limit (1 ppm for infant formula in China).
Co-reporter:Xianggang Liu, Xiangjin Qu, Hai Fan, Shiyun Ai, Ruixia Han
Electrochimica Acta 2010 Volume 55(Issue 22) pp:6491-6495
Publication Date(Web):1 September 2010
DOI:10.1016/j.electacta.2010.06.034
An electrochemical method for the detection of DNA hybridization using a novel electroactive, cationic, and water-soluble branched polyethyleneimine (BPEI)–cobalt(III)–phenanthroline(phen) polymeric indicator and single-stranded neutral peptide nucleic acid (PNA) probe on the Au electrode was developed. The indicator possesses some free amine groups, as well as cationic cobalt complexes in the polymer chain. It does not bind to neutral PNA capture probe alone. However, the indicator strongly interacts with the negatively charged backbone of the complementary oligonucleotide bound to the PNA probe through electrostatic interactions. The coordination spherical moieties also interact with the probe by embedding into the double-helix structure of PNA–DNA. These two interactions enable transduction of hybridization, producing a clear electrical signal in differential pulse voltammetry (DPV). The correlation against non-complementary DNA, three-base and one-base mismatch DNA was sharp, and the signal of indicator for the target DNA demonstrated a linear relationship within the concentration range of 5.0 × 10−9 to 2.5 × 10−7 M (R = 0.9940) with a detection limit of 5.6 × 10−10 M. These studies showed that the novel polymeric indicator and single-stranded PNA probe could be used to fabricate an electrochemical biosensor for DNA detection. This technique can provide an alternative route for expanding the range of detection methods available for DNA hybridization.
Co-reporter:Qiang Ma, Shiyun Ai, Huanshun Yin, Quanpeng Chen, Tiantian Tang
Electrochimica Acta 2010 Volume 55(Issue 22) pp:6687-6694
Publication Date(Web):1 September 2010
DOI:10.1016/j.electacta.2010.06.003
A novel amperometric sensor was fabricated based on the immobilization of hemin onto the poly (amidoamine)/multi-walled carbon nanotube (PAMAM/MWCNT) nanocomposite film modified glassy carbon electrode (GCE). Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and ultraviolet visible (UV–vis) adsorption spectroscopy were used to investigate the possible state and electrochemical activity of the immobilized hemin. In the Hemin/PAMAM/MWCNT nanocomposite film, MWCNT layer possessed excellent inherent conductivity to enhance the electron transfer rate, while the layer of PAMAM greatly enlarged the surface average concentration of hemin (Γ) on the modified electrode. Therefore, the nanocomposite film showed enhanced electrocatalytical activity towards the oxidation of l-tyrosine. The kinetic parameters of the modified electrode were investigated. In pH 7.0 phosphate buffer solution (PBS), the sensor exhibits a wide linear range from 0.1 μM to 28.8 μM l-tyrosine with a detection limit of 0.01 μM and a high sensitivity of 0.31 μA μM−1 cm−2. In addition, the response time of the l-tyrosine sensor is less than 5 s. The excellent performance of the sensor is largely attributed to the electro-generated high reactive oxoiron (IV) porphyrin (O = FeIV–P) which effectively catalyzed the oxidation of l-tyrosine. A mechanism was herein proposed for the catalytic oxidation of l-tyrosine by oxoiron (IV) porphyrin complexes.
Co-reporter:Huanshun Yin, Qiang Ma, Yunlei Zhou, Shiyun Ai, Lusheng Zhu
Electrochimica Acta 2010 Volume 55(Issue 23) pp:7102-7108
Publication Date(Web):30 September 2010
DOI:10.1016/j.electacta.2010.06.072
The graphene–chitosan composite film modified glassy carbon electrode (GCE) was fabricated and used to determine 4-aminophenol (4-AP). In 0.1 M pH 6.3 phosphate buffer solution, the redox peak currents of 4-AP increased significantly and the peak-to-peak separation decreased greatly at graphene–chitosan composite film modified GCE compared with bare GCE and chitosan modified GCE, indicating that graphene possessed electrocatalytic activity towards 4-AP. The experimental conditions were optimized and the kinetic parameters were investigated. The oxidation mechanism was discussed. Under the optimal experimental conditions, the oxidation peak current was proportional to 4-AP concentration in the range from 0.2 to 550 μM with the correlation coefficient of 0.9930. The detection limit was 0.057 μM (S/N = 3). Using the proposed method, 4-AP was successfully determined in water samples and paracetamol tablets with standard addition method, suggesting that this method can be applied to determine 4-AP in environments and pharmaceuticals.
Co-reporter:Huanshun Yin, Lin Cui, Shiyun Ai, Hai Fan, Lusheng Zhu
Electrochimica Acta 2010 Volume 55(Issue 3) pp:603-610
Publication Date(Web):1 January 2010
DOI:10.1016/j.electacta.2009.09.020
The electrochemical behavior of bisphenol A (BPA) was investigated on Mg–Al layered double hydroxide (LDH) modified glassy carbon electrode (GCE) by cyclic voltammetry (CV), differential pulse voltammetry (DPV), linear sweep voltammetry (LSV) and chronocoulometry (CC). The cyclic voltammogram of BPA on the modified electrode exhibited a well defined anodic peak at 0.454 V in 0.1 M pH 8.0 phosphate buffer solution (PBS). The experimental parameters were optimized and the kinetic parameters were investigated. The probable oxidation mechanism was proposed. Under the optimized conditions, the oxidation peak current was proportional to BPA concentration in the range from 1 × 10−8 to 1.05 × 10−6 M with the correlation coefficient of 0.9959. The detection limit was 5.0 × 10−9 M (S/N = 3). The fabricated electrode showed good reproducibility, stability and anti-interference. The proposed method was successfully applied to determine BPA in plastic products and the results were satisfactory.
Co-reporter:Huanshun Yin, Yunlei Zhou, Jing Xu, Shiyun Ai, Lin Cui, Lusheng Zhu
Analytica Chimica Acta 2010 Volume 659(1–2) pp:144-150
Publication Date(Web):5 February 2010
DOI:10.1016/j.aca.2009.11.051
An amperometric bisphenol A (BPA) biosensor was fabricated by immobilizing tyrosinase on multiwalled carbon nanotubes (MWNTs)-cobalt phthalocyanine (CoPc)-silk fibroin (SF) composite modified glassy carbon electrode (GCE). In MWNTs-CoPc-SF composite film, SF provided a biocompatible microenvironment for the tyrosinase to retain its bioactivity, MWNTs possessed excellent inherent conductivity to enhance the electron transfer rate and CoPc showed good electrocatalytic activity to electrooxidation of BPA. The cyclic voltammogram of BPA at this biosensor exhibited a well defined anodic peak at 0.625 V. Compared with bare GCE, the oxidation signal of BPA significantly increased; therefore, this oxidation signal was used to determine BPA. The effect factors were optimized and the electrochemical parameters were calculated. The possible oxidation mechanism was also discussed. Under optimum conditions, the oxidation current was proportional to BPA concentration in the range from 5.0 × 10−8 to 3.0 × 10−6 M with correlation coefficient of 0.9979 and detection limit of 3.0 × 10−8 M (S/N = 3). The proposed method was successfully applied to determine BPA in plastic products and the recovery was in the range from 95.36% to 104.39%.
Co-reporter:Huanshun Yin;Yunlei Zhou;Shiyun Ai;Xianggang Liu;Lusheng Zhu
Microchimica Acta 2010 Volume 169( Issue 1-2) pp:87-92
Publication Date(Web):2010 April
DOI:10.1007/s00604-010-0309-1
A glassy carbon electrode was modified with hydroxyapatite nanopowder (HA-NP) and characterized in terms of electrochemical oxidation of 4-nitrophenol (4-NP) via cyclic voltammetry, differential pulse voltammetry, chronoamperometry, and chronocoulumetry. The oxidation peak current of 4-NP at the modified electrode was increased (compared to the bare GCE), thus indicating that the HA-NP exhibits a remarkable enhancement effect on the electrochemical oxidation of 4-NP. The effects of loading with HA-NP, pH value, scan rate and accumulation time were examined. The oxidation peak current of 4-NP is proportional to its concentration in the range from 1.0 μM to 300 μM, with a correlation coefficient of 0.9996. The detection limit is 0.6 μM (at an S/N = 3). The method is simple, selective and sensitive. It was successfully applied to the determination of 4-NP in water samples, with recoveries ranging from 96% to 104%.
Co-reporter:Yanyan Qiu;Hai Fan;Xu Liu;Shiyun Ai;Tiantian Tang;Ruixia Han
Microchimica Acta 2010 Volume 171( Issue 3-4) pp:363-369
Publication Date(Web):2010 December
DOI:10.1007/s00604-010-0437-7
A glassy carbon electrode was modified with dsDNA and a nanocomposite composed of multi-walled carbon nanotubes and chitosan (MWNT-chit). The electrode was applied to the electrochemical detection of DNA damage as induced by in situ generated bisphenol A (BPA) radicals through electro-oxidation. The modified electrode was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The results indicate that MWNT-chit nanocomposite represents a viable platform for the immobilization of DNA that effectively promotes electron transfer between DNA and the electrode. The mode of interaction between DNA and BPA was investigated by differential pulse voltammetry and UV-vis spectrophotometry, indicating that the dominant interaction is intercalation. In order to explore the mechanism of damage caused by BPA radicals, the electro-oxidation of BPA at the modified glass electrode was investigated. Based on the signal for guanine without any other external indicator, DNA damage was investigated through the electro-oxidation of BPA.
Co-reporter:Huanshun Yin;Yunlei Zhou;Shiyun Ai;Ruixia Han;Tiantian Tang
Microchimica Acta 2010 Volume 170( Issue 1-2) pp:99-105
Publication Date(Web):2010/08/01
DOI:10.1007/s00604-010-0396-z
A glassy carbon electrode was modified with a composite made from gold nanoparticles and silk fibroin whose surface was further modified with amino-terminated G4 poly(amidoamine) dendrimer. This electrode shows distinct electrochemical response to bisphenol A (BPA). Electrochemical impedance spectroscopy was used to characterize the surface. The electrode displayed improved adsorption capacity and an increased response to BPA, compared to a surface without modification. Under the optimal detection conditions, the respeonse is linear in the concentration range from 1 nM to 1.3 μM, the correlation coefficient is 0.9991, and the detection limit is 0.5 nM (at an S/N of 3). The method was applied to the determination of BPA in water samples, and the recovery was in the range from 97% to 105%.
Co-reporter:Quanpeng Chen;Shiyun Ai;Qiang Ma;Huanshun Yin
Journal of Applied Electrochemistry 2010 Volume 40( Issue 7) pp:1379-1385
Publication Date(Web):2010 July
DOI:10.1007/s10800-010-0105-y
Determination of dopamine (DA) in the absence and presence of ascorbic acid (AA) by ferrocenyl-tethered PAMAM G3 dendrimers (Fc-D) modified glassy carbon electrode (GCE) was reported. The modified electrode was characterized with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Factors influencing the detection processes were optimized and kinetic parameters were calculated. The sensor exhibited excellent catalytic activities for the oxidation–reduction reactions of DA and eliminated the interference of AA. Under optimal condition, the linear range of 1 × 10−5–1.5 × 10−3 mol L−1 and the detection limit of 4.7 × 10−6 mol L−1 was obtained. This study provides a new idea for the determination of DA in the presence of AA.
Co-reporter:Quanpeng Chen;Shiyun Ai;Hai Fan;Jun Cai
Journal of Solid State Electrochemistry 2010 Volume 14( Issue 9) pp:1681-1688
Publication Date(Web):2010 September
DOI:10.1007/s10008-010-1010-3
A novel and sensitive biosensor was developed for the determination of nitrite. Firstly, multi-walled carbon nanotubes–poly(amidoamine)–chitosan (MWNT–PAMAM–Chit) nanocomposite along with the incorporation of DNA was used to modify the glassy carbon electrode. Then the immobilization of Cyt c was accomplished using electrochemical deposition method by consecutive cyclic voltammetry (CV) scanning in a neutral Cyt c solution. CV behaviors of the modified electrodes showed that the MWNT–PAMAM–Chit nanocomposite is a good platform for the immobilization of DNA and Cyt c in order, at the same time, an excellent promoter for the electron transfer between Cyt c and the electrode. At high potential, the immobilized Cyt c could be further oxidized into highly reactive Cyt c π-cation by two-step electrochemical oxidation, which could oxidize NO2− into NO3− in the solution. Therefore, a nitrite biosensor based on the biocatalytic oxidation of the immobilized Cyt c was fabricated, which showed a fast response to nitrite (less than 5 s). The linear range of 0.2–80 μM and a detection limit of 0.03 μM was obtained. Finally, the application in food analysis using sausage as testing samples was also investigated.
Co-reporter:Huanshun Yin, Yunlei Zhou, Qiang Ma, Shiyun Ai, Quanpeng Chen, Lusheng Zhu
Talanta 2010 Volume 82(Issue 4) pp:1193-1199
Publication Date(Web):15 September 2010
DOI:10.1016/j.talanta.2010.06.030
A graphene, chitosan and Fe3O4 nanoparticles (nano-Fe3O4) modified glassy carbon electrode (graphene–chitosan/nano-Fe3O4/GCE) was fabricated. The modified electrode was characterized by scanning electron microscope and electrochemical impedance spectroscopy. The electrochemical oxidation behavior of guanosine was investigated in pH 7.0 phosphate buffer solution by cyclic voltammetry and differential pulse voltammetry. The experimental results indicated that the modified electrode exhibited an electrocatalytic and adsorptive activities towards the oxidation of guanosine. The transfer electron number (n), transfer proton number (m) and electrochemically effective surface area (A) were calculated. Under the optimized conditions, the oxidation peak current was proportional to guanosine concentration in the range of 2.0 × 10−6 to 3.5 × 10−4 mol L−1 with the correlation coefficient of 0.9939 and the detection limit of 7.5 × 10−7 mol L−1 (S/N = 3). Moreover, the modified electrode showed good ability to discriminate the electrochemical oxidation response of guanosine, guanine and adenosine. The proposed method was further applied to determine guanosine in spiked urine samples and traditional Chinese medicines with satisfactory results.
Co-reporter:Quanpeng Chen, Shiyun Ai, Shasha Li, Jing Xu, Huanshun Yin, Qiang Ma
Electrochemistry Communications 2009 Volume 11(Issue 11) pp:2233-2236
Publication Date(Web):November 2009
DOI:10.1016/j.elecom.2009.09.038
The electrochemical inactivation of microorganisms using Escherichia coli as testing species by a novel PbO2 electrode was investigated. The PbO2 electrode was constructed by electrochemical deposition of PbO2 on the treated Ti substrate in the fluorine (F) doped ionic liquids/water (ILs/H2O) two phase solution. Then, it was characterized by XRD and SEM analysis. Further investigation showed that the crystal size of electrodeposited PbO2 became smaller with the increase of ILs concentration in the electrolyte solution. The small crystal size favored to the generation of the absorbable OHOH on the electrode surface, which was proved to play a key role during the disinfection process. TEM investigation revealed the morphological change of the E. coli cells during the bactericidal process.
Co-reporter:Xiangbin Zhu, Shiyun Ai, Quanpeng Chen, Huanshun Yin, Jing Xu
Electrochemistry Communications 2009 Volume 11(Issue 7) pp:1543-1546
Publication Date(Web):July 2009
DOI:10.1016/j.elecom.2009.05.055
A novel DNA electrochemical biosensor for label-free determination of DNA sequence related to the Avian Influenza Virus (AIV) genotype was demonstrated in this paper. First, the multi-walled carbon nanotubes–cobalt phthalocyanine (MWNTs–CoPc) nanocomposite and poly (amidoamine) (PAMAM) dendrimer (generation 4.0) were modified on the glassy carbon electrode (GCE) sequentially. Then, DNA probes were successfully immobilized on the modified electrode with G4 PAMAM dendrimer acting as the coupling agent. The hybridization events were monitored by differential pulse voltammetry (DPV) measurement based on the oxidation signals of guanine without any external labels. Under the optimal conditions, the difference in guanine oxidation signal of the probe modified GCE in the absence and presence of complementary target (ΔIp) was linear with the logarithmic value of the complementary target concentration from 0.01 to 500 ng/ml with a correlation coefficient of 0.998 and a detection limit of 1.0 pg/ml.
Co-reporter:Huanshun Yin, Shiyun Ai, Jing Xu, Weijie Shi, Lusheng Zhu
Journal of Electroanalytical Chemistry 2009 Volume 637(1–2) pp:21-27
Publication Date(Web):15 December 2009
DOI:10.1016/j.jelechem.2009.09.025
A new sensitive and stable amperometric biosensor for the detection of methyl paraoxon, carbofuran and phoxim had been developed based on immobilization of acetylcholinasterase (AChE) on gold nanoparticles (AuNPs) and silk fibroin (SF) modified platinum electrode. The SF provided a biocompatible microenvironment around the enzyme molecule to stabilize its biological activity and effectively prevented it from leaking out of platinum electrode surface. In the presence of acetylthiocholine chloride (ATCl) as a substrate, AuNPs promoted electron transfer reaction at a lower potential and catalyzed the electrochemical oxidation of thiocholine (TCh), thus increasing detection sensitivity. The influences of pH, enzyme loading, temperature and inhibition time on the response of the fabricated biosensor were investigated. Under optimum conditions, the inhibition percentages of methyl paraoxon, carbofuran and phoxim were proportional to their concentrations in the range of 6 × 10−11–5 × 10−8 M, 2 × 10−10–1 × 10−7 M and 5 × 10−9–2 × 10−7 M, respectively. The detection limits were found to be 2 × 10−11 M for methyl paraoxon, 1 × 10−10 M for carbofuran and 2 × 10−9 M for phoxim. Moreover, the fabricated biosensor had good reproducibility and acceptable stability. The biosensor is a promising new tool for pesticide analysis.
Co-reporter:Huan-shun Yin, Yun-lei Zhou, Shi-yun Ai
Journal of Electroanalytical Chemistry 2009 Volume 626(1–2) pp:80-88
Publication Date(Web):15 February 2009
DOI:10.1016/j.jelechem.2008.11.004
In this paper, a simple and high sensitive electroananlytical method for determination of bisphenol A (BPA) by using cobalt phthalocyanine (CoPc) modified carbon paste electrode (CPE) was presented. The electrochemical oxidation behavior of BPA on the modified electrode was investigated by cyclic voltammetry (CV), chronocoulometry (CC), differential pulse voltammetry (DPV), linear sweep voltammetry (LSV), and bulk electrolysis with coulometry. Factors influencing the detection processes were optimized and kinetic parameters were calculated. Under the optimal conditions, the oxidation peak current was proportional to BPA concentration in the range of 8.75 × 10−8–1.25 × 10−5 M with correlation coefficient 0.9987 and limits of detection 1.0 × 10−8 M. The electrooxidation mechanisms of BPA on the electrode surface and the proposed method applied for detection of BPA in plastic products were also discussed.
Co-reporter:Quanpeng Chen, Shiyun Ai, Xiangbin Zhu, Huanshun Yin, Qiang Ma, Yanyan Qiu
Biosensors and Bioelectronics 2009 Volume 24(Issue 10) pp:2991-2996
Publication Date(Web):15 June 2009
DOI:10.1016/j.bios.2009.03.007
A novel nitrite biosensor was successfully prepared via immobilizing Cytochrome c (Cyt c) onto the multi-walled carbon nanotubes–poly(amidoamine) (PAMAM)–chitosan (MWNT–PAMAM–Chit) nanocomposite modified glass carbon electrode (GCE). Ultraviolet and visible (UV–vis) absorption spectrum, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to examine the native conformation and bioactivity of the immobilized Cyt c, and the electrochemical properties of the modified electrodes, respectively. The results indicate that the immobilized Cyt c retained its native characters, and the MWNT–PAMAM–Chit nanocomposite is a good platform for the immobilization of Cyt c as well as an excellent promoter for the electron transfer between Cyt c and electrode. The high reactive Cyt c π-cation, which can oxidize NO2− into NO3− in the solution, is generated at higher potential (>0.7 V) based on the further oxidation of Cyt c. The nitrite biosensor showed a fast response to nitrite (about 5 s) in two concentration intervals, one was from 0.1 to 29 μM, and the other from 29 to 254 μM. The low detection limit of 0.01 μM was obtained.
Co-reporter:Huanshun Yin, Shiyun Ai, Weijie Shi, Lusheng Zhu
Sensors and Actuators B: Chemical 2009 Volume 137(Issue 2) pp:747-753
Publication Date(Web):2 April 2009
DOI:10.1016/j.snb.2008.12.046
The preparation of horseradish peroxidase (HRP)–gold nanoparticles (AuNPs)–silk fibroin (SF) modified glassy carbon electrode (GCE) by one step procedure was reported for the first time. The direct electrochemistry of HRP at the modified electrode was investigated. The enzyme electrode showed a quasi-reversible electrochemical redox behavior with a formal potential of −210 mV (vs. SCE) in 0.1 M phosphate buffer solution at pH 7.1. The response of the biosensor showed a surface-controlled electrochemical process with one electron transfer accompanying with one proton. The cathodic transfer coefficient was 0.42, the electron transfer rate constant was 1.84 s−1 and the surface coverage of HRP was 1.8 × 10−9 mol cm−2. The experimental results indicated that AuNPs–SF composite matrix could not only steadily immobilize HRP, but also efficiently retain its bioactivity. The biosensor displayed an excellent and quick electrocatalytic response to the reduction of H2O2.
Co-reporter:Shiyun Ai, Qingjiang Wang, Hui Li, Litong Jin
Journal of Electroanalytical Chemistry 2005 Volume 578(Issue 2) pp:223-229
Publication Date(Web):1 May 2005
DOI:10.1016/j.jelechem.2005.01.002
The formation of free hydroxyl radical (OH) in oxygen transfer reactions at PbO2 electrodes and the reaction between the electrochemically produced OH and salicylic acid (SA) were studied by cyclic voltammetry and capillary electrophoresis-amperometric detection (CZE-AD) in this paper. Experiments showed that OH was formed in the potential range of 1.0–1.4 V corresponding to the anodic discharge of H2O at the PbO2 electrode, while this phenomenon was not obvious at the Pt electrode. Optimum CZE-AD conditions for indirect determination of OH were explored. It was also found that when salicylic acid was used to trap OH produced on the PbO2 electrode surface, the amount of 2,5-dihydroxybenzoic acid produced is much more than that of 2,3-dihydroxybenzoic acid. This phenomenon is explained by the proposal that SA first forms an active aromatic radical on the PbO2 electrode surface before trapping OH, where OH performs a stronger preference in attacking at the 5-position than for attacking at the 3-position of the aromatic radical.
Co-reporter:Zhenwei Han, Nan Wang, Hai Fan, Shiyun Ai
Solid State Sciences (March 2017) Volume 65() pp:110-115
Publication Date(Web):March 2017
DOI:10.1016/j.solidstatesciences.2017.01.010
Co-reporter:Qingyang Li, Ping Man, Liqian Yuan, Pilan Zhang, Yan Li, Shiyun Ai
Molecular Catalysis (April 2017) Volume 431() pp:32-38
Publication Date(Web):1 April 2017
DOI:10.1016/j.mcat.2017.01.011
•LDH and derived LDO were prepared as support.•The supported Ru catalyst was employed used in HMF hydrogenation reaction.•Ru/CoFe-LDO exhibited good stability and catalytic activity.•The calcination temperature influences the activity and selectivity greatly.•The cooperation between metallic Ru and CoFe-LDO facilitates the process of HMF hydrogenation.A catalyst of ruthenium supported on CoFe layered double oxide (CoFe-LDO) allows selective hydrogenation of biomass-based 5-hydroxymethylfurfural (HMF) to the high-quality liquid fuel 2, 5-dimethylfuran (DMF) in the presence of tetrahydrofuran (THF). Under the optimal conditions, Ru/CoFe-LDO was exhibited higher catalytic performance, yielding 98.2% DMF with 100% HMF conversion at a relatively mild reaction temperature of 180 °C for 6 h. The structure and composition of the support and catalyst were investigated through a series of characterized methods Influence of various reaction parameters, such as reaction temperature, solvent Ru content of the catalyst and calcinations temperature of carrier etc., were explored with respect to HMF conversion and DMF yield. Although Ru/CoFe-LDO had a little loss in the catalytic activity after three successive reaction runs, the activity could be easily recovered by heating and reducing with hydrazine hydrate. Moreover our results also showed the cooperation between the metallic Ru site and the CoFe-LDO further facilitates the process of HMF hydrogenation to DMF.Download full-size image
Co-reporter:Lijian Chen, Bing Sun, Xindong Wang, Fengmin Qiao and Shiyun Ai
Journal of Materials Chemistry A 2013 - vol. 1(Issue 17) pp:NaN2274-2274
Publication Date(Web):2013/03/01
DOI:10.1039/C3TB00044C
In this report, a novel approach for exfoliation of Co–Al layered double hydroxides (LDHs) in aqueous solution of L-asparagine was proposed. L-Asparagine is a water-soluble amino acid whose carbonyl groups would have a strong interaction with the LDH host layers and the amino groups might weaken the interlayer interactions. This simple method did not need reflux at high temperature, overcame the drawback of using organic solvents, and even resulted in a stably stored colloidal suspension of 2D nanosheets. Besides, the peroxidase-like activity of the exfoliated Co–Al LDH (Co–Al ELDH) was enhanced compared with unexfoliated LDH. Co–Al ELDH could rapidly catalyze oxidation of the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2, producing a blue color reaction. On this basis, simple, rapid and selective colorimetric methods for H2O2 and glucose detection were developed. The presented means was used for glucose detection in fruit juices and fine results were obtained.
Co-reporter:Nan Wang, Bingchen Li, Fengmin Qiao, Jianchao Sun, Hai Fan and Shiyun Ai
Journal of Materials Chemistry A 2015 - vol. 3(Issue 39) pp:NaN7723-7723
Publication Date(Web):2015/08/25
DOI:10.1039/C5TB00684H
In this report, stable copper nanoparticles (Cu NPs) were prepared through a facile annealing process using humic acid as the reducing and stabilizing agents. The products were characterized by X-ray powder diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The prepared Cu NPs show remarkably intrinsic peroxidase-like activity, which can rapidly catalyze the oxidation of the peroxidase substrate, 3,3′,5,5′-tetramethylbenzidine (TMB), in the presence of H2O2 to produce a blue-color reaction. The detection limit of H2O2 by Cu NPs can be as low as 1.32 × 10−7 M. More importantly, the prepared Cu NPs show excellent stability, which can hardly be oxidized even after 6 months. Based on the aforementioned mechanism, a simple, rapid and selective colorimetric method for glucose detection was developed, and the detection limit of glucose was 6.86 × 10−7 M. This study provides a novel method for the preparation of stable Cu NPs, which may have widespread applications in the detection of glucose in the human body and pear juice.
Co-reporter:Zhengbin Tian, Qingyang Li, Juying Hou, Yan Li and Shiyun Ai
Catalysis Science & Technology (2011-Present) 2016 - vol. 6(Issue 3) pp:NaN707-707
Publication Date(Web):2015/12/23
DOI:10.1039/C5CY01864A
The selective hydrogenation of cinnamaldehyde and citral was investigated over platinum catalysts supported on Fe-based layered double hydroxides and derived mixed metal oxides. Among the catalysts, Pt/ZnFe-LDH showed the best activity and selectivity for the hydrogenation of CO bonds in cinnamaldehyde, and citral was mostly transformed into citronellol over the Pt/NiFe-LDH catalyst.
Co-reporter:
Analytical Methods (2009-Present) 2014 - vol. 6(Issue 7) pp:NaN2162-2162
Publication Date(Web):2014/01/13
DOI:10.1039/C3AY41820K
A new nonenzymatic electrochemical sensor was developed for sensitive detection of methyl parathion based on graphene nanosheets (GNs)/gadolinium Prussian Blue analogue (gadolinium hexacyanoferrate, GdHCF) modified glassy carbon electrode. The new sensor combined the individual properties of GNs (high conductivity and adsorption affinity) and GdHCF (high surface area and special catalytic activity), and realized efficient enrichment and electrochemical stripping voltammetric detection of methyl parathion. Under optimum conditions, the reduction current was proportional to methyl parathion concentration over the range from 0.008 to 10 μM with a detection limit of 1 nM. The sensor displayed high sensitivity, acceptable stability and selectivity, and realized reliable quantification of methyl parathion in practical environment samples.
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 11) pp:
Publication Date(Web):
DOI:10.1039/C3AY26599D
We have fabricated a sensitive acetylcholinesterase biosensor that is based on dual-signal amplification. A large amount of enzyme was immobilized on a glassy carbon electrode via specific binding between functionalized ZnSe quantum dots and acetylcholinesterase, and a graphene–chitosan nanocomposite was introduced that improves the response. These two factors render the biosensor highly sensitive to acetylthiocholine chloride. Organophosphate pesticides were detected with this biosensor using methyl parathion as a model enzyme inhibitor. Under optimal conditions, there is a linear relationship between the percentage of inhibition (I%) and the log of the concentration of methyl parathion in the 0.5 nM to 0.5 μM range, with a 0.2 nM detection limit (at an S/N of 3). The biosensor displays acceptable reproducibility and relatively good storage stability. It was successfully employed to the determination of methyl parathion in spiked water and soil samples.
Co-reporter:Xiaomeng Meng, Zhenning Xu, Mo Wang, Huanshun Yin and Shiyun Ai
Analytical Methods (2009-Present) 2012 - vol. 4(Issue 6) pp:NaN1741-1741
Publication Date(Web):2012/03/30
DOI:10.1039/C2AY00007E
A simple electrochemical method based on a Bi2S3 modified glassy carbon electrode (GCE) was developed to determine antipyrine using cyclic voltammetry and differential pulse voltammetry. Antipyrine shows a well-defined oxidation peak at the fabricated electrode in phosphate buffer solution and the oxidation peak current is much higher than that at the bare GCE, indicating that Bi2S3 can effectively improve the oxidation of antipyrine. Several effect factors on antipyrine determination were optimized, such as Bi2S3 amount, solution pH, scan rate and accumulation time. Under the optimal conditions, the oxidation peak current of antipyrine was proportional to its concentration in the range of 2.0 to 100 μM and 100 to 800 μM with a correlation coefficient of 0.9974 and 0.9956, respectively. The limit of detection was estimated to be 0.7 μM (S/N = 3). The developed method showed good reproducibility and excellent anti-interference performance. The fabricated electrode was successfully used to determine antipyrine in pharmaceutical formulations with recovery from 96% to 103.5%.
Co-reporter:Haichao Su, Bing Sun, Lijian Chen, Zhenning Xu and Shiyun Ai
Analytical Methods (2009-Present) 2012 - vol. 4(Issue 12) pp:NaN3986-3986
Publication Date(Web):2012/09/28
DOI:10.1039/C2AY25794G
A facile, economic and eco-friendly colorimetric detection method for dopamine has been well-established in this paper. It is based on the interaction between Cu2+ ions with amino group and hydroxyl groups of the dopamine adsorbed on the surface of gold nanoparticles (GNPs). Cu2+ ions serve as the selective “discriminator and linker” for dopamine detection. At high ionic strength, introduction of Cu2+ ions to GNPs solution including dopamine arouses the aggregation of GNPs, the color of the solution changes from wine red to blue, and the red shift of ultraviolet absorption peaks. The concentration of dopamine can be determined by monitoring with the naked eye or a UV-vis spectrometer. The calibration curve showed that the absorption ratio value at 650 and 525 nm (A650/A525) increased linearly over the dopamine concentration range of 5 × 10−7 M to 1 × 10−5 M with a limit of detection of 2 × 10−7 M (3σ). This method exhibits excellent selectivity for dopamine over other α-amino acids, glutathione, glucose, uric acid and ascorbic acid, and the process of the experiment, including the preparation of GNPs, detection of dopamine, pretreatment of sample, is finished within 30 min at room temperature. On the other hand, this probe was successfully applied to detect dopamine in human serum with high sensitivity, and this strategy may provide a selective sensing approach for measuring dopamine under physiological conditions.
Co-reporter:Zhiqing Yang, Wenjing Jiang, Fei Liu, Yunlei Zhou, Huanshun Yin and Shiyun Ai
Chemical Communications 2015 - vol. 51(Issue 78) pp:NaN14673-14673
Publication Date(Web):2015/08/12
DOI:10.1039/C5CC05921F
A novel electrochemical immunosensor was fabricated for the quantitative detection of 5-hydroxymethylcytosine (5-hmC) in genomic DNA based on anti-5-hmC antibody, biotin functionalized phos-tag and avidin functionalized alkaline phosphatase. It is demonstrated that the levels of 5-hmC are dramatically reduced in human breast cancer tissue compared with those in normal tissue.
Co-reporter:
Analytical Methods (2009-Present) 2012 - vol. 4(Issue 5) pp:NaN1451-1451
Publication Date(Web):2012/03/21
DOI:10.1039/C2AY05912F
A selective and sensitive electrochemistry method was developed for the determination of phenacetin on CdSe microspheres modified glassy carbon electrode (GCE). The electrode exhibited an effectively catalytic response to the oxidation of phenacetin, which was testified by the increased oxidation peak current and the decreased oxidation peak potential compared with the bare GCE. The scan rate investigation demonstrated that the electrochemical oxidation was an adsorption-controlled process in the range from 20 to 500 mV s−1. Under optimal determination conditions, the oxidation peak current of phenacetin was proportional to its concentration in the range of 0.5 to 800 μM. The limit of detection was estimated to be 0.1 μM (S/N = 3). The developed method showed good reproducibility, acceptable stability and excellent anti-interference performance. The fabricated electrode was successfully used to determine phenacetin in pharmaceutical formulation samples.
