Studies On The Electrodeposited Acetylcholinesterase Biosensor And Its Application In Pesticide Determination

Enzymes are the most powerful molecular recognition elements in biosensing, since the sensing signal can be amplified millions of times through enzymatic reactions. This signal amplification enables the designing of highly sensitive biosensing systems. Amperometric enzymatic biosensors have been considered to be the most suitable for biochemical analysis due to their good selectivity, sensitivity, rapid response, miniature size, and reproducible results. A combination of enzymatic reactions with electrochemical method allowed to develop different enzyme based electrochemical biosensors for sensitive and rapid determination of environmental analysis. Among these, amperometric acetylcholinesterase (AChE) biosensors based on the inhibition of AChE have shown satisfactory results for pesticides analysis, in which the enzymatic activity is employed as an indicator of quantitative measurement of insecticides.A significant challenge to development of sensitive and stable sensors comes from effective immobilization of enzyme to solid electrode surface. Electrochemical deposition has been reported recently as an effective immobilization method for enzyme due to the formation of sol-gel films.In our experiment, on the one hand, three different kinds of interfaces were constructed based on the electrodeposition of chitosan or gold nanoparticles. These interfaces displayed excellent biocompatibility and good stability for immobilization of AChE. Under the optimal electrodeposition, amperometric sensors for the fast determination of pesticide were developed. On the other hand, the immobilized AChE mediated hydrolysis of ATC1 and yielded a reducing agent thiocholine. A simple strategy for the design of an electrochemical sensor based on enzyme-induced growth of gold nanoparticles (AuNPs) without adding gold nano-seeds was proposed.Chemisorption/desorption process seems to be useful for determination of thiol compounds (and thiol-producing catalysts) with high sensitivity. We also applied the chemisorption/desorption process of thiocholine on a gold nanoparticles modified electrode to determine pesticide.To sum up, these proposed AChE biosensors could be readily extended toward the determination of pesticide and the investigation of medicine or pesticide sensitivity.