Sensitive Acetylcholinesterase Biosensor Based on Screen-Printed Carbon Electrode Modified with Cerium Oxide-Chitosan/Mesoporous Carbon-Chitosan for Organophosphorus Pesticide Residue Detection

A novel electrochemical acetylcholinesterase (AChE) biosensor modified with cerium oxide-chitosan (CeO2-CS) and ordered mesoporous carbon-chitosan (OMC-CS) using a screen-printed carbon electrode (SPCE) was fabricated to detect organophosphorus pesticides (OPs). Compared with a common electrode, SPCEs do not need to be polished, can be conveniently carried, and are suitable for on-site detection. CeO2 has good redox properties and a larger electron transfer rate. In addition, OMC has good electrical conductivity and a larger specific surface area, and chitosan (CS) has a considerable number of hydroxyl and amine groups in polymer chains, which have strong complexation ability. Herein, CeO2-CS and OMC-CS were modified in the SPCE layer by layer to improve the electrochemical response and increase the fixed amount of AChE. The results obtained with this biosensor revealed that its sensitivity was significantly improved. Taking into account the possible interaction between the test conditions, the experimental parameters were optimized using a quadratic orthogonal rotation combination design to achieve a high electrochemical signal. The properties of AChE/OMC-CS/CeO2-CS/SPCE were characterized by differential pulse voltammetry and cyclic voltammetry techniques. Under optimum conditions, the fabricated acetylcholinesterase biosensor showed great reproducibility and high stability. In addition, the as-prepared AChE biosensor was successfully utilized for analysis of OPs in vegetables.