Du_2008_Talanta_74_766

Based on the change in electrochemical behavior of enzymatic activity induced by pesticide, a novel electrochemical method for investigation of pesticide sensitivity using acetylcholinesterase (AChE) biosensor was developed. The sol-gel-derived silicate network assembling gold nanoparticles (AuNPs-SiSG) provided a biocompatible microenvironment around the enzyme molecule to stabilize its biological activity and prevented them from leaking out of the interface. The composite was characterized using atomic force microscopy and proved to be chemically clean, porous and homogeneous. AuNPs promoted a conductive pathway for electron transfer and improved electrochemical reactions at a lower potential. Typical pesticides such as monocrotophos, methyl parathion and carbaryl were selected for pesticide sensitivity tests. Due to the inhibitions of pesticides, the electrochemical responses of substrate on AChE-sensors decreased greatly. The inhibition curves showed good correspondence with the results by UV spectrophotometry assay. The proposed electrochemical pesticide sensitivity test exhibited high sensitivity, desirable accuracy, low cost and simplified procedures. This method could be developed as a conventional method to select efficient enzyme inhibitors and investigate toxic compounds against to enzyme.