The Studies And Applications Of Four Kinds Of Novel Molecular Imprinted Electrochemical Sensors

Molecularly imprinted polymer (MIP) is a new kind of macromolecular material with high molecular recognition characteristics. Owing to predetermined property with specific recognition capability and wide practicability, it has been developed quickly in recent years. Compared with natural antibody, MIP can be easily prepared in large quantities and it also showed much higher stability even under extreme conditions. In this dissertation, four kinds of new molecularly imprinted electrochemical sensors were developed by combining molecularly imprinted technology with electric chemistry analysis technology.The main work of this thesis is summarized as follows:(1) The 2-mercaptobenzimidazole and L-tryptophan are selected as monomer and template molecule,respectively,the molecular imprinting coating which could be used to detect L-tryptophan is prepared directly on the surface of a gold electrode by cyclic voltammetry method.Because of L-tryptophan has no electrical activity, the potassium ferricyanide was used as a molecular probe to detect L-tryptophan by constant potential amperometry. The response achieve stable in 100 s. The sensor exhibited good selectivity and sensitivity to L-tryptophan. The linear range for the determination of L-tryptophan is from 3.10×10-5 to 8.83×10-4 mol?L-1,and the best detectability condition of this sensor were discussed.(2) A molecularly imprinted polymer was prepared by molecular imprinted technique using 2-aminothiophenol as monomer,Sudan I as template molecule. The sensitive film was prepared through the electropolymerization of o-aminophenol on a gold electrode in the presence of template (Sudan I). Cyclic Voltammetry and Amperometric i-t Curve are used to study on the molecular recognition and binding characteristics in Sudan I molecularly imprinted polymer. The sensor exhibited good selectivity and sensitivity to Sudan I. The determination limit was 5.0×10-8 mol?L-1, and a linear relationship between the current and the concentration was found in the range of 5.00×10-7~2.00×10-5 mol?L-1. The recovery rates of Sudan I ranging from 93.3%~108.6%.(3) Preparation of a molecularly imprinted polymer (MIP) film and its recognition property for atrazine are investigated. The 2-mercaptobenzimi- dazole polymer film was deposited in 2-mercaptobenzimidazole solution with and without a template molecule (atrazine) on a gold electrode by cyclic voltammetric technology. The performance of the imprinted and non- imprinted (NIP) film were evaluated by cyclic voltammetry (CV). The performance of the imprinted film was investigated and optimized. The molecularly imprinted film exhibited a high selectivity and sensitivity toward atrazine. The reduction peak current of atrazine depended on the concentration of atrazine at the range of 1.2×10-8～8.0×10-5 mol?L-1 and the detection limit was 3.0×10-9 mol?L-1 (r =0.9986). The sensor has been applied to the analysis of atrazine in soil samples with recovery rates ranging from 90.8% to 98.2%, indicating that this method has good accuracy.(4) Preparation of a molecularly imprinted electrode and its recognition property for lysozyme was investigated. The polypyrrole film was prepared by the cyclic voltammetric deposition of pyrrole on a glassy carbon electrode. The performance of the imprinted electrode was evaluated by electrochemical impedance method.Several important parameters controlling the performance of the electrode was optimized. The molecularly imprinted electrode exhibited a high selectivity and sensitivity toward lysozyme. Imprinted electrode showed a stable and reproducible to lysozyme in the mixture solutions.