Single substrate-functionalized molybdenum oxide nanozyme for specific colorimetric monitoring of xanthine oxidase activity.

Abstract

Xanthine-functionalized molybdenum oxide nanodots (X-MoO3-x NDs) with peroxidase (POD)-like activity were developed for selective, sensitive, and facile colorimetric quantification of xanthine oxidase (XO). Xanthine functionalization can not only be favorable for the successful nanozyme preparation, but also for the specific recognition of XO as well as the simultaneous generation of hydrogen peroxide, which was subsequently transformed into hydroxyl radical to oxidize the chromogenic reagent based on the POD-like catalysis. Under the optimized conditions, the colorimetric biosensing platform was established for XO assay without addition of further substrates, showing good linearity relationship between absorbance difference (ΔA) and XO concentrations in the range 0.05-0.5 U/mL (R2 = 0.998) with alimit of detection (LOD) of 0.019 U/mL. The quantification of XO occursin 25 min, which is superior to the previously reported and commercial XO assays. Theproposed method has been successfully used in theassay of human serum samples, showing its highpotential in the field of clinical monitoring.