Amperometric biosensor based on immobilized acetylcholinesterase on goldnanoparticles and silk fibroin modified platinum electrode for detection of methylparaoxon, carbofuran and phoxim

摘要

A new sensitive and stable amperometric biosensor for the detection of methyl paraoxon, carbofuran andphoxim had been developed based on immobilization of acetyicholinasterase (AChE) on gold nanoparti-des (AuNPs) and silk fibroin (SF) modified platinum electrode. The SF provided a biocompatible micro-environment around the enzyme molecule to stabilize its biological activity and effectively preventedit from leaking out of platinum electrode surface. In the presence of acetylthiocholine chloride (ATCl)as a substrate, AuNPs promoted electron transfer reaction at a lower potential and catalyzed the electro-chemical oxidation of thiocholine (TCh), thus increasing detection sensitivity. The influences of pH,enzyme loading, temperature and inhibition time on the response of the fabricated biosensor were inves-tigated. Under optimum conditions, the inhibition percentages of methyl paraoxon, carbofuran and phox-im were proportional to their concentrations in the range of 6 x 10~(-11)-5 x10~(-8)M,2 10)-1x 10~(-7)Mand 5 x 10~(-9)-2x 10~(-7)M, respectively. The detection limits were found to be2 x 11)M for methylparaoxon, 1 x 10~(-10)M for carbofuran and2 x 10~(-9)phoxim. Moreover, the fabricated biosensorhad good reproducibility and acceptable stability. The biosensor is a promising new tool for pesticideanalysis.