Kinetics Difference-driven Organophosphorus Hydrolase-like Nanozyme-Coded Pattern for Identifying p-Nitrophenyl Pesticides

Organophosphorus pesticides (OPs) are widely used in agricultural production, posing a great threat to human health and the environment. Given that different OPs present different toxicology and toxicities, identifying individual pesticide residues becomes important for assessing food safety and environmental implications. In this work, a kinetics difference-driven analyte hydrolysis strategy is proposed for the first time and validated to identify p-nitrophenyl pesticides by developing an organophosphorus hydrolase-like nanozyme-coded sensor array. Ultrasmall bare CeO₂ nanoparticles were synthesized and employed as the only sensing unit to catalyze the hydrolysis of multiple analytes. With catalytic preferences and kinetics differences under identical reaction conditions, five common OPs analogues (methyl-paraoxon, paraoxon, methyl-parathion, parathion, and fenitrothion) offered discriminable colors. By coupling the color fingerprints with pattern recognition, the accurate identification of individual p-nitrophenyl pesticides and their mixtures at a variety of concentrations and ratios was verified in laboratory and practical scenarios. Attractively, apart from excellent performance and convenient operation, the proposed hydrolytic nanozyme-coded pattern presents strong resistance against redox substances that often cause interference in previous oxidoreductase-based sensor arrays. Our study provides a new paradigm of discriminating specific OPs precisely, showing promising applications in multitarget analysis in complex matrices.