A new electrochemical sensor for organophosphate pesticide (methyl-paraoxon) detection based on bifunctional cerium oxide (CeO₂) nanozyme is here reported for the first time. Methyl-paraoxon was degraded into p-nitrophenol by using CeO₂ with phosphatase mimicking activity. The CeO₂ nanozyme-modified electrode was then synthesized to detect p-nitrophenol. Cyclic voltammetry was applied to investigate the electrochemical behavior of the modified electrode, which indicates that the signal enhancement effect may attribute to the coating of CeO₂ nanozyme. The current research also studied and discussed the main parameters affecting the analytical signal, including accumulation potential, accumulation time, and pH. Under the optimum conditions, the present method provided a wider linear range from 0.1 to 100 μmol/L for methyl-paraoxon with a detection limit of 0.06 μmol/L. To validate the proof of concept, the electrochemical sensor was then successfully applied for the determination of methyl-paraoxon in three herb samples, i.e., Coix lacryma-jobi, Adenophora stricta and Semen nelumbinis. Our findings may provide new insights into the application of bifunctional nanozyme in electrochemical detection of organophosphorus pesticide.

本文首次报道了一种基于双功能氧化铈（CeO ₂）纳米酶的新型有机磷农药（甲基对氧磷）检测电化学传感器。使用具有磷酸酶模拟活性的CeO _{2 将}甲基对氧磷降解为对硝基苯酚。然后合成CeO ₂纳米酶修饰电极以检测对硝基苯酚。应用循环伏安法研究修饰电极的电化学行为，表明信号增强效应可能归因于CeO ₂的涂层纳米酶。目前的研究还研究和讨论了影响分析信号的主要参数，包括积累潜力、积累时间和pH值。在最佳条件下，本方法为甲基对氧磷提供了较宽的线性范围，从 0.1 到 100 μmol/L，检出限为 0.06 μmol/L。为了验证概念验证，随后将电化学传感器成功应用于测定三种药草样品中的甲基对氧磷，即薏苡仁、沙参和莲心。我们的发现可能为双功能纳米酶在有机磷农药电化学检测中的应用提供新的见解。