Two-Dimensional MnO2 Nanozyme-Mediated Homogeneous Electrochemical Detection of Organophosphate Pesticides without the Interference of H2O2 and Color

Traditional peroxidase-like nanozyme-based sensors suffer from selfdecomposition and high toxicity of H2O2, as well as the interference of color from nanozymes themselves and testing samples. In this work, we adopt nanozymes (twodimension (2D) MnO, sheets, manganese dioxide nanosheets (MnNS)) with oxidase-like and peroxidase-like properties as advanced catalysts to develop a novel homogeneous electrochemical sensor for organophosphate pesticides (OPs) using dissolved O-2 as a coreactant without the interference of H2O2 and color. Owing to the large surface area and unique catalytic activity of MnNS, a large amount of tetramethylbenzidine (TMB) is catalyzed oxidation, leading to a significantly declined differential pulse voltammetry (DPV) current. Obviously, MnNS display an excellent response to thiocholine, deriving from the catalyzing hydrolysis of acetylthiocholine (ATCh) by acetylcholinesterase (AChE), which switches a homogeneous electrochemical OP detection process based on the depressing AChE activity with a limit of detection (LOD) of 0.025 ng mL(-1). The as-proposed strategy on using nanozymes with oxidase-like and peroxidase-like properties to develop a homogeneous electrochemical sensor will provide a new pathway for improving the performance of nanozyme-based sensors, and the established MnNS-based homogeneous electrochemical sensor will find more applications for OP residue determination in food samples.

Automated summary

In this study, manganese dioxide nanosheets were used as catalysts to develop a novel electrochemical sensor for organophosphate pesticides detection, eliminating interference from H2O2 and color. The sensor showed improved performance and lower detection limits, providing a new pathway for nanozyme-based sensors and finding more applications in food samples for OP residue determination.