酮戊二酸接枝壳聚糖-纳米金粒子复合物固定漆酶基电极的催化氧还原性能

以α－酮戊二酸接枝壳聚糖和纳米金溶胶共混所得复合物为固定漆酶的载体，将固酶复合物滴涂在裸玻碳电极表面干燥后，得到固定漆酶基阴极。文章考察了此电极在不含底物的电解质溶液中的直接电化学行为，同时还考察了其在扩散型电子中介体存在时的异相电子迁移动力学，同时研究了此电极对氧气还原反应的催化性能（中介体存在时）。在此基础上进一步考察了此电极作为氧气电化学传感器的性能。研究结果表明：α－酮戊二酸接枝壳聚糖一纳米金溶胶复合物固定漆酶修饰电极在无电子中介体时不能实现漆酶活性中心与电极之间的直接电子迁移，也不具备催化氧还原的性能。在扩散型电子中介体存在时，该电极能在较高的电位（催化氧还原的起始电位：790mV）下实现氧气的电还原，而且对氧气浓度较为敏感。这种漆酶基电极的在生理pH值时仍具有一定的催化活力。这种电极对氧的传感性能良好：检测限低达0．5×10－6mol／L、灵敏度高达35．6×10-6AL／mmol和良好的对氧亲和力（KM=89．9×10mol／L）。

Catalytic Function on Oxygen Reduction Reaction of Composite Made up of Nano--Gold Sol and a--Ketoglutaric Acid Grafted Chitosan with Entrapped Laccase Modified Electrode

This article adopted the composite made up ofa--ketoglutaric acid grafted Chitosan and nano --gold sol which was obtained by mechanical mixing as carrier for laccase entrapment. Laccase based bio- cathode was prepared by complex with entrapped enzyme dripping and coating on the surface of bare glassy carbon electrode and drying process in air consecutively. The direct electrochemical behavior of this as-- prepared electrode in the electrolyte without any substrate was investigated, furthermore its heterogeneous electron transfer dynamics in the presence of diffusional mediator and its catalytic function for oxygen re- duction reaction （ORR） were systematically evaluated on the basis of previous experiment. Results from research indicate that composite composed of nano--gold sol and a--ketoglutaric acid grafted Chitosan with entrapped enzyme modified electrode can＇t achieve electron transfer between active centre in laccase and the electrode in the absence of any extra electron relay and can＇t catalyze oxygen electrochemical re- duction either. The as--prepared laccase based cathode can catalyze the oxygen reduction reaction （ORR） under high potential （onset potential for ORR was 790 mV） and was sensitive to the concentration of oxy- gen molecule. This laccase based electrode retained certain catalytic active under physiological pH value. This laccase base electrode was proved to be a suitable sensor for oxygen molecules, its detection limit low to 0.5 × 10-6 mol/L）, high sensitivity： 35.6 × 10-6 A L/mmol and preferable affinity for oxygen （KM =89.9× 10.6 mol/L）.