Study And Application Of The Film Chemically Modified Electrodes In Chemical Sensors And Biosensors

The film chemically modified electrodes are prepared by designing the electrode surfaces on the molecule level and immobilizing the molecules, ions and polymers of the specifically chemical and electrochemical properties on electrode surfaces to provide the modified electrodes with the specifically chemical and electrochemical functions, which enriched the electrode materials and expanded the research field of the electrochemistry. It was for the moment widely applied in many cases such as life science, environmental science, energv sources science, analytic science, electronics and material science. The mediator modified on the surface of electrodes can accomplish the electrocatalytic reactions by accelerating electron transferring between redox centers and the electrode surface. The electro catalysis of the modified electrode is an enormous impetus for its development and is widely used in the slow electron transferring processes which isn't easily realized, for example, the electro catalysis of biomolecules, organic compounds and inorganic ions. The substances immobilized on the modified electrodes are applied for the separation and accumulation of the analytes to accomplish the good selectivity and the high sensitivity of the analytical processes. 1. In our papers, the glycine was modified on the surface of glassy-carbon electrode by the oxidative electropolymerization of CV to fabricate the polyglycine modified electrodes. The high sensitivity and good selectivity were accomplished in the determination of the dopamine due to the selective penetration and the accumulative effect of the.polyglycine membrane. The method to make dopamine sensors is very easy and convenient. The obtained electrode is prone to be reproducible. The dopamine sensor effectively avoided the serious interference from the ascorbic acid and made it possible to determine them at the same time in some condition.2. The pyrogallol was adhered on the surface of the solid electrode by the direct oxidative electropolymerization to construct the chemical sensors for Bi (III) . The sensor exhibits perfect long stability and reproducibility. A low detection was obtained in the determination of Bi(III) and this way can be applied to determine the real samples such as human hair and nails.3. A novel composite material (Ag0n- ZP) consisting of nano colloidal silver and solid zirconium phosphate was firstly synthesized and applied for the preparation of chemically modified electrodes after it adsorbed the dye molecules such as neutral red. The zirconium phosphate reduced the agglomeration degree of the anodize silver colloid in aqueous medium and improved the catalytic activity of Ag0n. The silver colloid in the composite material never changed the ability of ZP to tune the potential of redox mediators. But the ability of the zirconium phosphate to adsorb neutral red and the redox reaction ability of this phenothiazine dye were enhanced significantly in the composite film due to the nanosize silver colloid. This experiment optimized the performances of ZP and Ag0n An effective way to fix the mediator was put forward in our paper.4. The H2O2 biosensor was constructed with the film made from the Ag0n- ZP colloid with HRP, BSA and glutaraldehyde. This sensor had the significant effect of electro catalytic effect on the reduction of H2O2. Its catalytic current was linear with the concentration of H2O2. Most of interference was effectively eliminated and the inactivity of HRP under the too low potential to catalytize the reduction of H2O2 was avoided due to the enhanced potential of NR by ZP in the composite film. While the silver colloid in the composite film enhanced the capability of ZP to adsorb NR and prevented effectively NR from leaching off. This job greatly extended the use of NR in the biosensors.