Fabricating theranostic nanoparticles combining multimode disease diagnosis and therapeutic has become an emerging approach for personal nanomedicine. However, the diagnostic capability, biocompatibility, and therapeutic efficiency of theranostic nanoplatforms limit their clinic widespread applications. Targeting to the theme of accurate diagnosis and effective therapy of cancer cells, a multifunctional nanoplatform of aptamer and polyethylene glycol (PEG) conjugated MoS2 nanosheets decorated with Cu1.8S nanoparticles (ATPMC) is developed. The ATPMC nanoplatform accomplishes photoluminescence imaging, photoacoustic imaging, and photothermal imaging for in vitro and in vivo tumor cells imaging diagnosis. Meanwhile, the ATPMC nanoplatform facilitates selective delivery of gene probe to detect intracellular microRNA aberrantly expressed in cancer cells and anticancer drug doxorubicin (DOX) for chemotherapy. Moreover, the synergistic interaction of MoS2 and Cu1.8S renders the ATPMC nanoplatform with superb photothermal conversion efficiency. The ATPMC nanoplatform loaded with DOX displays near-infrared laser-induced programmed chemotherapy and advanced photothermal therapy, and the targeted chemo-photothermal therapy presents excellent antitumor efficiency.

Multifunctional theranostic platform coupling diagnostic and therapeutic functions holds great promise for personalized nanomedicine. Nevertheless, integrating consistently high performance in one single agent is still challenging. This work synthesized a sort of porphyrin derivatives (P) with high singlet oxygen generation ability and graphene quantum dots (GQDs) possessing good fluorescence properties. The P was conjugated to polyethylene glycol (PEG)ylated and aptamer-functionalized GQDs to gain a multifunctional theranostic agent (GQD-PEG-P). The resulting GQD-PEG-P displayed good physiological stability, excellent biocompatibility and low cytotoxicity. The intrinsic fluorescence of the GQDs could be used to discriminate cancer cells from somatic cells, whereas the large surface facilitated gene delivery for intracellular cancer-related microRNA (miRNA) detection. Importantly, it displayed a photothermal conversion efficiency of 28.58% and a high quantum yield of singlet oxygen generation up to 1.08, which enabled it to accomplish advanced photothermal therapy (PTT) and efficient photodynamic therapy (PDT) for cancer treatment. The combined PTT/PDT synergic therapy led to an outstanding therapeutic efficiency for cancer cell treatment.Keywords: graphene quntaum dots; intracellular microRNA detection; photothermal/photodynamic therapy; porphyrin derivative; theranostic nanostructure;

Herein, an efficient electrochemical tracer with advanced oxygen reduction reaction (ORR) performance was designed by controllably decorating platinum (Pt) (diameter, 1 nm) on the surface of compositionally tunable tin-doped indium oxide nanoparticle (Sn–In2O3) (diameter, 25 nm), and using the Pt/Sn–In2O3 as electrochemical tracer and interfacial term hairpin capture probe, a facile and ultrasensitive microRNA (miRNA) detection strategy was developed. The morphology and composition of the generated Pt/Sn–In2O3 NPs were comprehensively characterized by spectroscopic and microscopic measurements, indicating numerous Pt uniformly anchored on the surface of Sn–In2O3. The interaction between Pt and surface Sn as well as high Pt(111) exposure resulted in the excellent electrochemical catalytic ability and stability of the Pt/Sn–In2O3 ORR. As proof-of-principle, using streptavidin (SA) functionalized Pt/Sn–In2O3 (SA/Pt/Sn–In2O3) as electrochemical tracer to amplify the detectable signal and a interfacial term hairpin probe for target capture probe, a miRNA biosensor with a linear range from 5 pM to 0.5 fM and limit of detection (LOD) down to 1.92 fM was developed. Meanwhile, the inherent selectivity of the term hairpin capture probe endowed the biosensor with good base discrimination ability. The good feasibility for real sample detection was also demonstrated. The work paves a new avenue to fabricate and design high-effective electrocatalytic tracer, which have great promise in new bioanalytical applications.

Small size molybdenum disulfide (MoS2) quantum dots (QDs) with desired optical properties were controllably synthesized by using tetrabutylammonium-assisted ultrasonication of multilayered MoS2 powder via OH-mediated chain-like Mo–S bond cleavage mode. The tunable up-bottom approach of precise fabrication of MoS2 QDs finally enables detailed experimental investigations of their optical properties. The synthesized MoS2 QDs present good down-conversion photoluminescence behaviors and exhibit remarkable up-conversion photoluminescence for bioimaging. The mechanism of the emerging photoluminescence was investigated. Furthermore, superior 1O2 production ability of MoS2 QDs to commercial photosensitizer PpIX was demonstrated, which has great potential application for photodynamic therapy. These early affording results of tunable synthesis of MoS2 QDs with desired photo properties can lead to application in fields of biomedical and optoelectronics.Keywords: bioimaging; MoS2 quantum dots; photodynamic therapy (PDT); ultrasonic preparation; up-conversion fluorescence

•A high performance ORR catalyst of Pt/SnO2/C nanofiber was fabricated.•The catalyst exhibits competitive ORR catalytic activity compared to the Pt/C catalyst.•The catalyst displays enhanced methanol tolerance and superior durability.•The mechanism of enhanced ORR catalytic activity was explored.•It provides a guideline for designing analogous structure ORR catalyst.In this report, an efficient oxygen reduction reaction (ORR) electrocatalyst of platinum (Pt) decorated SnO2/C (Pt/SnO2/C) nanofiber was fabricated by using a Pt galvanic displacement of a copper (Cu) layer electrodeposited on electrospinning SnO2/C nanofiber. Microscopic and spectroscopic characterizations revealed that the facile electrospinning and galvanic displacement route generated numerous dispersed Pt nanoparticles on the SnO2/C nanofiber; and Pt nanoparticles (d ~ 2–3 nm) with high composition of Pt (111) facet were preferably deposited at the SnO2/C junctions to form triple junction nanostructures. The resulting Pt/SnO2/C nanocomposite presented an onset potential of 0.02 V vs RHE, specific activity of 1.12 mA cm− 2 and mass activity of 615 mA/mgPt at − 0.05 V vs RHE. It is competitive to commercial Pt/C (10 wt% Pt) catalyst toward ORR. Notably, in comparison with commercial Pt/C, the composition displayed superior electrochemical durability and enhanced methanol tolerance. It was demonstrated that the presence of Pt/SnO2/C triple junction nanostructures coupled with high composition of Pt (111) facets synergistically contributed the enhanced ORR activity, while the good conductivity of the C facilitates the electron transfer during the ORR process. The metal-metal oxide-carbonaceous heterogeneous structure represents a promising platform for designing ORR catalysts with high performance.

A highly sensitive and multiple microRNA (miRNA) detection method by combining three-dimensional (3D) DNA tetrahedron-structured probes (TSPs) to increase the probe reactivity and accessibility with duplex-specific nuclease (DSN) for signal amplification for sensitive miRNA detection was proposed. Briefly, 3D DNA TSPs labeled with different fluorescent dyes for specific target miRNA recognition were modified on a gold nanoparticle (GNP) surface to increase the reactivity and accessibility. Upon hybridization with a specific target, the TSPs immobilized on the GNP surface hybridized with the corresponding target miRNA to form DNA–RNA heteroduplexes, and the DSN can recognize the formed DNA–RNA heteroduplexes to hydrolyze the DNA in the heteroduplexes to produce a specific fluorescent signal corresponding to a specific miRNA, while the released target miRNA strands can initiate another cycle, resulting in a significant signal amplification for sensitive miRNA detection. Different targets can produce different fluorescent signals, leading to the development of a sensitive detection for multiple miRNAs in a homogeneous solution. Under optimized conditions, the proposed assay can simultaneously detect three different miRNAs in a homogeneous solution with a logarithmic linear range spanning 5 magnitudes (10–12–10–16) and achieving a limit of detection down to attomolar concentrations. Meanwhile, the proposed miRNA assay exhibited the capability of discriminating single bases (three bases mismatched miRNAs) and showed good eligibility in the analysis of miRNAs extracted from cell lysates and miRNAs in cell incubation media, which indicates its potential use in biomedical research and clinical analysis.Keywords: duplex-specific nuclease; multiple microRNA detection; signal amplification; tetrahedral DNA nanostructures; ultrasensitive microRNA detection;

Photoluminescent (PL) graphene quantum dots (GQDs) with large surface area and superior mechanical flexibility exhibit fascinating optical and electronic properties and possess great promising applications in biomedical engineering. Here, a multifunctional nanocomposite of poly(l-lactide) (PLA) and polyethylene glycol (PEG)-grafted GQDs (f-GQDs) was proposed for simultaneous intracellular microRNAs (miRNAs) imaging analysis and combined gene delivery for enhanced therapeutic efficiency. The functionalization of GQDs with PEG and PLA imparts the nanocomposite with super physiological stability and stable photoluminescence over a broad pH range, which is vital for cell imaging. Cell experiments demonstrate the f-GQDs excellent biocompatibility, lower cytotoxicity, and protective properties. Using the HeLa cell as a model, we found the f-GQDs effectively delivered a miRNA probe for intracellular miRNA imaging analysis and regulation. Notably, the large surface of GQDs was capable of simultaneous adsorption of agents targeting miRNA-21 and survivin, respectively. The combined conjugation of miRNA-21-targeting and survivin-targeting agents induced better inhibition of cancer cell growth and more apoptosis of cancer cells, compared with conjugation of agents targeting miRNA-21 or survivin alone. These findings highlight the promise of the highly versatile multifunctional nanocomposite in biomedical application of intracellular molecules analysis and clinical gene therapeutics.Keywords: cell imaging; gene therapeutics; graphene quantum dots; microRNAs; survivin;

•A facile and sensitive microRNA biosensor was designed.•It allowed detection of miRNA with the limit of detection down to 0.045 pM.•The stre-GNRs tag was readily served as promising amplification labels in SPR sensing technology.•It employed interfacial biotinylated thiolated DNA molecular beacon as probe.•It was readily served as a powerful ultrasensitive sandwich assay for miRNA detection.Herein, a facile and sensitive microRNA (miRNA) biosensor was designed by using interfacial biotinylated thiolated DNA molecular beacon (MB) as probe and streptavidin functionalized gold nanorods (Stre-GNRs) as tag for the enhanced surface plasmon resonance (SPR) signal. The MB probe with two terminals labeled with biotin and thiol groups, respectively, was modified on the gold film via thiol-gold interaction. Upon hybridization with the target, the biotinylated group became accessible to the Stre-GNRs. The introduction of the Stre-GNRs tag to the gold film produced strong SPR signal for detection. Our work has illustrated that the plasmonic field extension generated from the gold film to GNRs and the mass increase due to the GNRs have led to drastic sensitivity enhancement. Under optimal conditions, this proposed approach allowed detection of miRNA with the limit of detection (LOD) down to 0.045 pM. The results have shown that the MB probe functionalized sensing film, together with streptavidin-conjugated GNRs, was readily served as a plasmonic coupling partner that can be used as a powerful ultrasensitive sandwich assay for miRNA detection, and GNRs were readily served as promising amplification labels in SPR sensing technology.