Highly Sensitive Molecularly Imprinted Electrochemical Sensor Based On The Amplification By Catalytic Polymer

The molecular imprinted technique （MIT） has taken more and more respect fromresearchers due to its predetermination, selective recognition, and wide use. Molecularimprinted electrochemical sensors （MIECS） combine the strong points both molecularlyimprinted polymers and electrochemical sensors, showed simple preparation, high stability,long lifetime, resistance to bad environment, and so on.Consequently, in this paper, new materials （Conducting Polymers, CP） and methods areapplied to MIT, and some new MIECS of oxytetracycline （OTC） and chlortoluron （CH） areconstructed successfully by coupling these imprinted matrices with electric transducers. Themain contents are listed as follows:（1） A novel strategy to improve the sensitivity of molecularly imprinted polymer （MIP）sensors was proposed. An electrocatalytic Prussian blue （PB） film was electrochemicallypolymerized on an electrode surface to fabricate an MIP electrochemical sensor usingoxytetracycline （OTC） as a template. The OTC determination relied on a competition reactionbetween OTC and glucose oxidase-labeled OTC and the catalytic reduction of hydrogenperoxide by the modified PB film. Experimental results show that double amplification,which is based on the catalysis of inorganic PB films and the enzymatic effect of glucoseoxidase, can remarkably increase the assay sensitivity. The main experimental conditions（including electrocatalysis of the PB film, pH effects, incubation and competition times, andanti-interference） were optimized. This novel MIP sensor can offer a0.23nmol/L detectionlimit for OTC. In addition, the feasibility of its practical applications has been demonstratedin the analysis of a series of real milk samples.（Chapter1）（2） A novel strategy to improve the sensitivity of molecularly imprinted polymers sensor（MIP-sensor） for oxytetracycline （OTC） determination was prepared. An electrocatalyticPoly-methylene blue （PMB） film was used to act as the polymer of MIP electrochemicalsensor. The determination is mainly based on the catalytic reduction of hydrogen peroxide onPMB film. A competition reaction between ultratrace OTC and horseradishperoxidase-labeled oxytetracycline （HRP-OTC） was occurred by measured OTC. Thesensitivity increased remarkably due to the double amplification by catalysis of PMB film andenzymatic effect of HRP. The experimental conditions of optimization were described,including electrocatalysis of PMB film, pH effects, incubation time, competition time andanti-interference. A linear range of0.6²5nmol/L for OTC detection with a detection limit （DL） of0.15nmol/L was gained. In addition, The MIP sensor has been applied for OTCdetermination in milk sample; it displayed the feasibility of its practical applications.（Chapter2）（3） Molecular imprinted films were prepared on GC electrode for the determination ofchlortoluron （CH）, which existed in environment as residue of pesticide. The detection of CHrelied on a competition reaction between CH and HRP-CH coupled with the subsequentcatalytic reduction of H₂O₂by the MA film. The double amplification based on the inorganiccatalytic MA film and the enzymatic effect of HRP has been verified to favor the highlysensitive detection of CH. The experimental conditions of optimization were described,including electrocatalysis of MA film, pH effects, incubation time, competition time andanti-interference. Linear ranges of0.01⁰.1μmol/L and0.1⁰.8μmol/L for CH detectionwith a detection limit （DL） of2.64nmol/L. The developed MA-assisted MIECS showedexcellent analytical performance （e.g., high sensitivity, good selectivity, and goodreproducibility） and has great potential for further development as a general and promisingalternative sensor for a wide range of applications.（Chapter3）...