title: Immobilization of acetylcholinesterase on gold nanoparticles embedded in sol-gel film for amperometric detection of organophosphorous insecticide.
abstract: A simple method to immobilize acetylcholinesterase (AChE) on silica sol-gel (SiSG) film assembling gold nanoparticles (AuNPs) was proposed, thus a sensitive, fast and stable amperometric sensor for quantitative determination of organophosphorous insecticide was developed. The large quantities of hydroxyl groups in the sol-gel composite provided a biocompatible microenvironment around enzyme molecule and stabilized its biological activity to a large extent. The immobilized AChE could catalyze the hydrolysis of acetylthiocholine chloride (ATCl) with a Kmapp value of 450 microM to form thiocholine, which was then oxidized to produce detectable single with a linear range of 10-1000 microM. AuNPs catalyzed the electro-oxidation of thiocholine, thus increasing detection sensitivity. Based on the inhibition of organophosphorous insecticide on the enzymatic activity of AChE, using monocrotophos as a model compound, the conditions for detection of the insecticide were optimized. The inhibition of monocrotophos was proportional to its concentration ranging from 0.001 to 1 microg/ml and 2 to 15 microg/ml, with the correlation coefficients of 0.9930 and 0.9985, respectively. The detection limit was 0.6 ng/ml at a 10% inhibition. The developed biosensor exhibited good reproducibility and acceptable stability, thus providing a new promising tool for analysis of enzyme inhibitors.
authors.affiliation: Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, Central China Normal University, Wuhan 430079, PR China. dudan@mail.ccnu.edu.cn
authors.forename: Dan
authors.initials: D
authors.lastname: Du
authors.forename: Shizhen
authors.initials: S
authors.lastname: Chen
authors.forename: Jie
authors.initials: J
authors.lastname: Cai
authors.forename: Aidong
authors.initials: A
authors.lastname: Zhang
mesh_terms: D000110:Acetylcholinesterase / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D002800:Cholinesterase Inhibitors / Q000032:analysis*; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004800:Enzymes, Immobilized / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006046:Gold / Q000737:chemistry*; D008567:Membranes, Artificial; D053758:Nanoparticles / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000032:analysis*; D044367:Phase Transition; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002800:Cholinesterase Inhibitors; D004800:Enzymes, Immobilized; D008567:Membranes, Artificial; D009943:Organophosphorus Compounds; D006046:Gold; D000110:Acetylcholinesterase