A cobalt-based polyoxometalate nanozyme with high peroxidase-mimicking activity at neutral pH for one-pot colorimetric analysis of glucose

Abstract

Thanks to the attractive merits of excellent robustness, easy large-scale production, and low cost, peroxidase-mimicking nanomaterials (nanozymes) are being used as promising alternatives to horseradish peroxidase in various applications. However, most of the currently developed peroxidase nanozymes only work in acidic media, which seriously hinders their use in biological systems. In this contribution, we reported a new cobalt-based polyoxometalate (CoPW₁₁O₃₉) with high peroxidase-like activity at neutral pH. With the negatively charged surface, the nanozyme exhibited strong ability to catalyze the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine into its blue product mediated by H₂O₂ under physiological conditions. Considering that the CoPW₁₁O₃₉ nanozyme and glucose oxidase (GOx) have a similar pH for catalytic activities, a one-pot colorimetric assay based on the combination of GOx and the peroxidase nanozyme was developed for glucose detection. Our assay has advantages of easy operation and fast detection, providing excellent accuracy for the monitoring of glucose in human plasma. These unique characteristics endow the polyoxometalate nanozyme with bright prospects in biochemical analysis.