Fabrication of CeVO4 as nanozyme for facile colorimetric discrimination of hydroquinone from resorcinol and catechol

Abstract

A simple method was proposed for the preparation of CeVO4. The as-synthesized CeVO4 was, for the first time, demonstrated to exhibit both peroxidase-like and oxidase-like activity, which catalyzes the oxidation of 3, 3′, 5, 5′-tetramethylbenzidine (TMB) to form a typical blue solution in the presence or absence of H2O2. Moreover, the mechanism of its dual-enzyme activity was investigated in detail. The Michaelis constant (Km) value for CeVO4 (0.136mM) was lower than that of horseradish peroxidase (0.424mM) with TMB as the substrate. Interestingly, hydroquinone (H2Q), dihydroxybenzene isomer, undergoes reduction accompanying the oxidation of TMB by the CeVO4 oxidase mimic along with a visible color change, while the other two dihydroxybenzene isomers, i.e., resorcinol (RC) and catechol (CC), do not. Based on these findings, a colorimetric platform was developed to discriminate H2Q from RC and CC. Under optimal conditions, a linear relationship between the H2Q concentration and absorbance was observed from 0.05 to 8μM, and a limit of detection of 0.04μM was achieved. Moreover, this colorimetric platform can selectively reveal H2Q concentrations in the presence of other dihydroxybenzene isomers.