•In this study, NaYF4:Yb, Tm@NaYF4:Yb nanoparticles with enhanced fluorescence were synthesized.•Upconversion nanoparticles and MoS2 was combined by aptamer to form a FAUM nanoplatform for MC-LR detection. To the best of our knowledge, this is the first time to detect MC-LR using energy transfer from enhanced fluorescence of CS-UCNPs to MoS2. The calibration curve for MC-LR detection with an excellent correlation (R2 of 0.9942) was achieved by fluorescence over the range of 0.01–50 ng/ml, and the LOD was calculated to be 0.002 ng/ml.•This aptamer-based platform might be a promising strategy for a variety of sensing applications.Water safety is one of the most pervasive problems afflicting people throughout the world. Microcystin-LR (MC-LR), a representative toxin released by cyanobacteria, poses an increasing and serious threat to water safety. In order to develop facile, specific and sensitive detection methods for MC-LR, we fabricated an ultrasensitive fluorescence aptasensor using the enhanced fluorescence of UCNP and the effective quenching ability, high affinity toward single strand DNA (ssDNA) of MoS2 (termed as FAUM). This assay specifically determined MC-LR in the linear range of 0.01–50 ng/ml with a limit of detection (LOD) of 0.002 ng/ml. The real water sample results indicated that this FAUM assay owns well enough reliability and feasibility to allow the determination of MC-LR. This aptamer-based method might be a promising strategy for a variety of sensing applications.

A high-affinity ssDNA aptamer that specifically binds to T-2 toxin was generated by the systemic evolution of ligands by exponential enrichment (SELEX) procedure assisted by graphene oxide (GO). After 10 rounds of selection against T-2 toxin, a highly enriched ssDNA pool was sequenced and the representative aptamers were subjected to binding assays to evaluate their affinity and specificity. Circular dichroism spectroscopy was also used to study the inherent interaction of T-2 toxin and the preferred aptamer Seq.16, which demonstrated a low dissociation constant (Kd) of 20.8 ± 3.1 nM and excellent selectivity for T-2 toxin. Using the selected aptamer Seq.16 as the recognition element, an aptamer-based fluorescent bioassay was developed for the measurement of T-2 in beer samples with a linear range from 0.5 to 37.5 μM (R2 = 0.988) and a limit of detection (LOD) of 0.4 μM. The results indicate that GO–SELEX technology is appropriate for the screening of aptamers against small-molecule toxins, offering a promising application for aptamer-based biosensors.

•A SERS-based aptasensor was developed for bacteria detection.•Au@Ag core–shell nanoparticles were used as SERS active substrate.•The method was sensitive and specific by using aptamers as recognition elements.•The technique shows potential for sensitive detection of pathogens in food safety.Surface-enhanced Raman spectroscopy (SERS) has been used in a variety of biological applications due to its high sensitivity and specificity. Here, we report a SERS-based aptasensor approach for quantitative detection of pathogenic bacteria. A SERS substrate bearing Au@Ag core/shell nanoparticles (NPs) is functionalized with aptamer 1 (apt 1) for the capture of target molecules. X-rhodamine (ROX)-modified aptamer 2 (apt 2) is used as recognition element and Raman reporter. Salmonella typhimurium specifically interacted with the aptamers to form Au@Ag-apt 1-target-apt 2-ROX sandwich-like complexes. As a result, the concentration of S. typhimurium was determined using this developed aptasensor structure, and a calibration curve is obtained in the range of 15 to 1.5 × 106 cfu/mL with a limit of detection of 15 cfu/mL. Our method was successfully applied to real food samples, and the results are consistent with the results obtained using plate counting methods. We believe that the developed method shows potential for the rapid and sensitive detection of pathogenic bacteria in food safety assurance.