KINETICS OF GLUCOSE-OXIDASE CATALYZED ELECTRON-TRANSFER MEDIATED BY SULFUR AND SELENIUM-COMPOUNDS

Unusually high electron transfer rates in Aspergillus niger glucose oxidase catalyzed oxidation of glucose using 5,6:11,12-Bis(dithio)tetracene (TTT), 1,2-dimethyltetraselenafulvalene (DMTSF) and tetrathiafulvalene (TTF) were observed. At pH 7.0 oxidation rate constants (TN/K(m)) in the range from 1.0 . 10(7) to 8.7 . 10(7) M . s-1 were deduced from experimental data. One of the investigated mediators, DMTSF, has been used for electrocatalytical glucose oxidation on graphite at a potential of 0.3 V vs. a standard calomel electrode (SCE). The prepared bioelectrodes have a sensitivity of 1.3 muA/(cm2 . mM), a pH optimum at 6.5-7.0, and a linear range which covers the relevant range for monitoring physiological levels of glucose. The bioelectrodes are stable for more than one month.