Double Signal Amplification of Electrochemical Sensor of Acetylcholinesterase for Detection of Organophosphate Pesticide

A novel,fast and sensitive electrochemical biosensor based on biometallization and silverenhancing for continuous signal amplification was described for the detection of organophosphate pesticide(OP).Malathion was used as a model to confirm our strategy.In this method,the immobilized acetylcholinesterase(AChE) mediated the hydrolysis of acetylthiocholine(ATCl) to yield a reducing agent thiocholine which reduced AuCl 4-to form gold nanoparticles(AuNPs).The electrode was then immersed in the silver enhancer solution containing 1.0 mol/L NH 3 and 2.0×10-3mol/L AgNO 3,and under the condition of #0.10 V as deposition potential,the metal silver was only deposited on the surface of AuNPs instead of the electrode surface for continuous signal amplification.The deposited silver was then quantified by linear sweep voltammetry(LSV).In the presence of malathion,the decrease in the stripping peak currents of silver was proportional to the concentration of malathion from 0.1 μg/L to 1000 μg/L,and the linear equation is i pa=149.9-40.49lgC(r=0.9963).The detection limit was found to be as low as 0.05 μg/L.The utilization of biometallization and silver deposition for continuous signal amplification to detect OP dramatically enhanced the sensitivity of AChE electrochemical biosensors.The sensor has been applied to analysis of OP in the water of Xiangjiang River with a satisfactory recovery rates ranging from 95.5% to 102.2%,showing a great potential for the OP assay.