Research Of Bioelectrochemistry Sensors For Organic Peroxides

The use of electrochemical techniques to study horseradish peroxidase and its active sites has gained increasing attention. Electrochemical methods can be used not only to imitate the electron transfer mechanism of organism, but also to combine the speciality of biological recognition element with the advantages of eletrochemical methods such as higher sensitivity and operation in situ.Horseradish peroxidase plays important roles in biological systems. In the thesis, electrodes are modified by bioaffinitic materials to investigate the electrochemical and electrocatalytic properties of horseradish peroxidase, summarized as the following.(1) Horseradish peroxidase was immobilized on glassy carbon electrodes by carrageenan. Horseradish peroxidase entrapped in the carrageenan film undergoes fast direct transfer-electron reaction in ethanol/PBS mixture. The formal potential are linearly dependent on solution pH (redox Bohr effect), indicating the electron transfer of Fe(Ⅲ)/Fe(Ⅱ)redox couple companied with the transfer of proton. Ultraviolet visible suggest that horseradish peroxidase keep its original conformation in the carrageenan films, and conformation changes reversibly in a range of pH 3.0-10.0. The machanisms for catalytic reduction of oxygen, hydrogen peroxide and organic peroxides by horseradish peroxidase entrapped in carrageenan were also explored.(2) Horseradish peroxidase and thionine were immobilized on glassy carbon electrode surface by carrabeenan hydrogel for fabricating an organic peroxide biosensor. Thionone, as a good electron mediator in the reaction that peroxides were reduced catalytically by horseradish peroxidase, performances quasi-reversible electrochemical reaction. The biosensor shows fast response, high sensitivity, good stability and reproducibility.