Acetylcholinesterase biosensor based on the mesoporous carbon/ferroferric oxide modified electrode for detecting organophosphorus pesticides

Abstract

In this paper a biosensor modified by ordered mesoporous carbon–chitosan (OMC–CS)/ferroferric oxide–chitosan (Fe₃O₄–CS) was developed on the surface of screen-printed carbon electrodes (SPCEs). The acetylcholinesterase (AChE) was modified onto the film to prepare an AChE biosensor. Chitosan was used as a dispersant to disperse OMC and Fe₃O₄. The OMC and Fe₃O₄ were used to enhance the electrochemical response. Before the detection of organophosphorus (OP) pesticides, the electrochemical behaviour of AChE/OMC–CS/Fe₃O₄–CS/SPCE was studied with cyclic voltammetry, and the results showed that the chitosan can disperse OMC and Fe₃O₄ evenly and fix them on the electrode surface firmly. OMC and Fe₃O₄ have a significant synergistic effect towards electron transfer. The parameters affecting performance, such as the pH of the test solution, the amount of AChE and the time of inhibition have been optimized. Under optimum conditions, using methamidophos and chlorpyrifos as model compounds, this biosensor showed a wide range, low detection limit, good reproducibility and high stability. Moreover, the AChE/OMC–CS/Fe₃O₄–CS/SPCE biosensor can be used for the detection of real samples, and is suitable for field testing of OP pesticide residues.