Selective detection of glutathione by flower-like NiVO with only peroxidase-like activity at neutral pH.

In view of the broad application prospect of peroxidase-like nanozymes in biomedical analysis, it is of great significance to eliminate the interference of their oxidase-like activity and enable them to work under neutral conditions. Herein, flower-like NiVO was synthesized and their enzyme-mimicking activity was investigated. Through the regulation of pH, NiVO nanozyme showed only peroxidase-like activity but not oxidase-like activity under neutral conditions, which could catalyze the oxidation of colorless 3,3',5,5'-tetramethylbenzidine into its blue product in the presence of HO. Furthermore, based on the competitive effect of glutathione (GSH) on the catalytic activity of nanozymes, a semi-quantitative/quantitative colorimetric assay was established for GSH detection by using peroxidase-like NiVO. The assay exhibited a good linear relationship in GSH concentration ranging from 3-100 μmol L, with a detection limit of 0.89 μmol L. Moreover, in the presence of formaldehyde as masking agent, this method showed satisfactory specificity for GSH under the interference of a variety of interfering substances and even biothiols. Concerning the practical application, the system was applied to monitor GSH level in fetal bovine serum, human serum and SiHa cells. Satisfyingly, the obtained results were consistent well with those of Ultra performance liquid chromatography (UPLC) and assay kit, indicating the constructed assay has great potential in clinical application.