A novel colorimetric strategy for rapid detection of dimethoate residue in vegetables based on enhancing oxidase-mimicking catalytic activity of cube-shape Ag2O particles

Although many colorimetric methods have been established for pesticide analysis, most of them rely on inhibiting catalytic activities of natural enzymes or nanozyme, easily leading to false positives in results of pesticide detection. Herein, a simple, stable, and rapid colorimetric method was firstly proposed to detect pesticide residues in vegetables based on enhancing the oxidase-mimicking activity of cube-shape Ag2O. The experiments, including fluorescence probe, electrochemistry, free radical tracking and enzymatic kinetics, confirmed that dimethoate could promote electron transfer from Ag2O to dissolved oxygen and accelerate the release of·O2- radicals as well as 1O2, facilitating the catalytic oxidation of the chromogenic substrate. The colorimetric method exhibited satisfactory sensitivity with the limit of detection as low as 14 μg·L−1. Moreover, such method showed excellent selectivity against other competitive pesticides, and achieved good recovery in several typical vegetables, which indicate that such strategy has a bright application prospect in the field of pesticide detection in food.