Studies On Acetylcholinesterase Biosensor Based On New Modification Strategy

China is an agricultural country.In the last decades,pests and diseases have always been one of the main factors affecting agricultural production.With the development of science and technology,organic phosphorus pesticides are widely used in agricultural production due to their low toxicity,high efficiency,and strong selectivity.However,large-scale use has led to security risks of organophosphorus pesticide residues in crops,affecting everyone's life,health and safety.Therefore,it is necessary to develop a detection technology that can measure organophosphorus pesticide residues in food quickly,easily,and accurately.Over the past few decades,the technology for accurately detecting organophosphorus pesticide residues has been greatly developed.Existing techniques for detecting organic phosphorus residues include gas chromatography,liquid chromatography,chromatography-mass spectrometry,enzyme-linked immunoassay,electrochemical biosensors and so on.Among them,electrochemical biosensors have been widely studied for their ability to detect organophosphorus pesticide residues quickly,accurately,simply and low cost.Based on the detection principle of electrochemical biosensors,this thesis studies and develops two acetylcholinesterase electrochemical biosensors based on new modification strategy.The main research work and results of this article are as follows:(1)Based on the basic principle that acetylcholinesterase would be inhibited by organophosphorus pesticides,an electrochemical experiment platform that can prepare,characterize,and test biosensors was established.Relevant technical information was collected to complete the structural design,material selection,parameters optimization,testing process and other basic work content.(2)An acetylcholinesterase electrochemical biosensor based on silver nanowire/graphene composite modified electrodes was prepared.The biosensor uses silver nanowires and graphene composite modified electrodes as a new modification strategy for electrochemical signal amplification.A titanium oxide and chitosan mixed sol-gel film was used as a fixed substrate and chitosan was used to adsorb and fix acetylcholinesterase.Under the premise of optimizing the test parameters,the sensor has a detection range of 36 n M/L to 22.63 ?M/L and the limit of detection of 7.4 n M/L.And the biosensor was proved to be a stable,sensitive,accurate organophosphorus pesticide sensor with actual sample detection capability.(3)A novel acetylcholinesterase electrochemical biosensor with patterned structure was prepared.The biosensor adopts a new modification strategy of patterning process,which avoids the obstruction of electrical signals by electrode modification materials not related to electrochemical signal transmission.Under the premise of optimized manufacturing process parameters,the detection range of the biosensor for dichlorvos is 1.13 n M/L to 22.63 ?M/L and the limit of detection is 0.23 n M/L.And the biosensor was proved to be a sensitive,accurate organophosphorus pesticide sensor with actual sample detection capabilities.