Multiwall Carbon Nanotube-Based Acetylcholinesterase Biosensor for Detecting Organophosphorous Pesticides

摘要

In order to develop a biosensor for detecting the organophosphate pesticides residues, a novel acetylcholinesterase biosensor based on immobilized enzyme membrane-electrode separating sensor was proposed, in which electrode was modified with multiwall carbon nanotubes, and acetylcholinesterase was cross-linked with glutaraldehyde and then attached to chitosan membrane. During the detection, the enzyme membrane was fixed on the surface of multiwall carbon nano-tubes/glassy carbon electrode with O-ring and thus the amperometric acetylcholinesterase-multiwall carbon nanotubes/glassy carbon electrode sensor was used for detecting organophosphate pesticides. The new sensor exhibited good electrocatalytic behavior towards the electro-oxidation of thio-choline. Thus amplified response current of the biosensor and improved detection sensitivity. Based on the inhibition of organophosphate pesticides to the enzymatic activity of acetylcholinesterase, using dichlorvos as a model compound, the conditions for detecting the pesticide were explored. Under optimal conditions, the response current was proportional to the concentration of dichlorvos range from 5 μg/L to 50μg/L with the correlation coefficient of 0.9921. The detection limit was 3 μg/L, far below the maximum residue level (100 μg/L) established by European Union for residues of the dichorvos in the vegetables and fruits. The biosensor exhibited good reproducibility and stability and provided a new method for detecting organophosphate pesticides residues.