Activity and inhibition by pesticides of acetylcholinesterase (AChE) is extensively applied to vast areas in science and technology, including pharmaceutical, health, food, agriculture, environmental monitoring and quality control. AChE is used in the production of enzymatic biosensors(EBS), based on its specific activity inhibition by organophosphorus and carbamate insecticides. Because of its incomparable advantages to traditional methods in the detection of pesticide residues, EBS has become a trend in pesticide residues detection. Much research has been conducted on preparing AChE biosensors and application to environmental monitoring and food inspection. The electrochemical character of AChE biosensor, such as stability, sensitivity, detection limit and response time, are limited by enzyme emmobilization. Hence, the means of immobilizing enzyme is the key in developing an EBS. Enzymatic activity depends on the enzyme conformation, thus, using a superior biocompatibility carrier is the common means for stable enzymatic conformation. In this work, PAMAM, which has a multitude of biocompatibility amino groups (-NH2) on its surface, is added between immobilization carriers and AChE. A novel amperometric biosensor of AChE is fabricated with PAMAM, and the amino groups (-NH2) on immobilization carriers are conducive to the stability of immobilized enzyme conformation and the increasing sensitivity of the EBS, which is confirmed by cyclic voltammetry, chronoamperometry and Ac impedance methods. In addition, with the generation of PAMAM becoming higher, there will be more amino groups on the surface of the immobilization carrier, also the stability and sensitivity of immobilized AchE will increase. These data suggest that the EBS of AChE with PAMAM of high generation is preferred. To investigate this phenomenon, computer simulation is used on PAMAM of different generation intereaction (G2.0, G3.0, G4.0) with AChE. The result shows that the total energy sequence of PAMAM with AChE is G2.0>G3.0>G4.0. It concludes that it is more stable between AChE and high generation of PAMAM, which is consistent with the experimental data.

AChE biosensors based on PAMAM dendrimers of different generations

248th National Meeting (2014)

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