Molecular Imprinted Sensors Based On Novel Electrosynthesized Polymers And An Immunosensor For New Castledisease Antibody Assay

Electrosynthesized polymers applied to molecular imprinting technology have been proved very efficient in construction of chemical sensors of excellent performance in terms of selectivity and stability. Electropolymerization methods have some attractive features including the easy adherence of the polymeric films to the surface of conducting electrodes of any shape and size and the ability to control thickness and porosity of the films by adjusting scan rate and time during electropolymerization. Since molecular imprinted sensors based on electrosynthesized polymers are few in the literature, a further exploration is necessary with a view of introducing novel electrosynthesized molecular imprinted polymers to chemical sensors. In this thesis, the author tried to develop novel chemical sensors based on electrosynthesized molecularly imprinted polymers as sensitive layers.For this purpose, in part one, two compounds, i.e. poly[2-mercaptobenzimidazole] (PMBI) and poly [2-mercaptobenzoxazole] (PMBO) were electrosynthesized as molecular imprinting polymers. (1) A cholesterol-selective sensor based on PMBI film has been prepared. Concentration of cholesterol up to 100M could be detected with a linear determination range up to 20M and a detection limit of 0.7M. The molecular imprinting approach offers a relatively nice selectivity for the sensor toward cholesterol with respect to common coexisting substances. (2) A capacitive chemical sensor for fenvalerate has been reported. In conjunction with the use of AC impedance measurements, this sensor has been based on the decrease in capacitance caused by the analyte used as the template in the formulation of electropolymerized molecularly imprinted polymer as receptor layer. The insulating properties of the sensor were inves-tigated in detail. Concentration of fenvalerate up to 9g/ml could be detected with a linear determination range up to 5g/ml and a detection limit of 0.36g/ml. No significant interference was observed from the common pyrethroid insecticides. (3) Abiomimetic amperometric sensor has been reported. The sensor is based on a poly[2-mercaptobenzoxazole](PMBO) film directly electrosynthesized on the gold surface as the matrix and the target analyte abscisic acid (ABA) is used as the template. Concentration of ABA up to 4.3g/ml could be detected with a linear determination range up to 1.0g/ml and a detection limit of 70ng/ml.In part two, an amperometric immunosensor system for Newcastle disease antibody (ND.Ab) assay has been developed. The Newcastle disease antigen (ND.Ag) was immobilized in a graphite paste matrix. The assay procedure is based on the bioreaction of the analyte ND.Ab and enzyme labeled HRP-ND.Ab competing for the ND.Ag sites at the newly regenerated biocomposite surface. The determination is accomplished by amperometry using tetramethylbenzidine and H2O2 as the substrates. Two different graphite pastes were compared using either sol-gel or solid paraffin as binders. The sol-gel biocomposite showed a better response characteristics and higher reproducibility. The ND.Ab can be determined up to 443.24 ng/ml with a detection limit of 190 ng/ml. The recovery studies in serum samples show the feasibility of practical application of the proposed method.