Feiyang Wang

Continuously evolving ‘chemical tongue’ biosensor for detecting proteins

We developed a unique continuously evolving colorimetric sensor array based on AuNPs decorated by two single-stranded oligonucleotides with different molar ratios for protein discrimination. The number of differential receptors in this sensor array could be easily extended by adjusting the molar ratios of two DNA, resulting in continuously improved discrimination ability. The continuous response data of target samples against our sensing system could be easily obtained and exclude abnormal signals. The sensing system could discriminate twelve proteins at the concentration of 200nM in the presence of 50% human urine with accuracy of 100%, showing feasible potential for diagnostic applications. Remarkably, HSA at various concentrations, the pure Lys and HSA, and the mixture of these two proteins with different molar ratios had been successfully discriminated in LDA plot as well in the presence of human urine sample. This novel strategy will be very promising for the design of cheaper and more reliable sensor arrays for target samples.

Rapid and sensitive colorimetric detection of ascorbic acid in food based on the intrinsic oxidase-like activity of MnO2 nanosheets

In this paper, we report a colorimetric sensor for the rapid, selective detection of ascorbic acid (AA) in aqueous solutions. Single-layered MnO2 nanosheets were established as an artificial oxidase; consequently colorless 3,3´,5,5´-tetramethylbenzidine (TMB) was oxidized to a blue product (oxTMB), with increase in absorbance at 650 nm. The absorbance of the reaction system decreased after introduction AA, which reduced MnO2 into Mn2+ . Under optimum conditions, a detection limit of 62.81 nM for AA in aqueous solutions could be achieved. The linear response range for AA was 0.25-30 μM with a correlation coefficient of 0.996. Importantly, the MnO2 nanosheet-TMB chromogenic reaction exhibited great selectivity as there was no interference from other metal ions, amino acids and small biological molecules. The proposed colorimetric sensing of AA could be applied for fruit, juice and pharmaceutical samples. Moreover, the proposed sensor showed satisfying performance, including low cost, easy preparation, rapid detection, and good biocompatibility.