The enzyme glucose oxidase (GOx) has high chemical stability and specificity with glucose, and has thus generated great interest with regard to the development of biosensors and bioanodes for use in biofuel cells. For developing biodevices, it is very important to achieve direct electron transfer (DET) between the active center of the enzyme and the electrode. However, for GOx, the cofactor flavine adenine dinucleotide (FAD) is located very deep in the enzyme structure, and this causes some difficulties in DET between the active center and the electrode surface. In this context, as part of investigating DET, we focused on the decrease in the distance between the cofactor FAD and the electrode surface. This decrease can be achieved by modifying the electrode surface. We have utilized chemically treated flexible carbon fibers as the working electrode to achieve the DET of GOx. After the chemical treatment, graphene oxides were formed on the surface of the fibers, and these GO approximates the FAD on the electrode surface, which facilitates DET. By subjecting this working electrode to cyclic voltammetry, we achieved the DET of GOx. This enabled us to study the effects of temperature and pH on this process. In studying the effect of temperature, we calculated the activation energy for both, oxidation and reduction processes: 6.49 and 12.26 kJ mol-1, respectively. Further, upon studying the effect of pH, it was concluded that the optimum pH for DET lies in the range 7.0-7.5. The average value obtained from the difference between the peak potentials was 0.023: thus value was close to the theoretical value for a reversible two-electron reaction (0.0295). Further, the slope of the graph for E1/2versus pH was -49 mV/pH; this value was close to the theoretical value (-59 mV/pH) for a reversible reaction between two protons and two electrons.

Direct electron transfer of glucose oxidase on graphene oxides-modified flexible carbon fiber electrode

247th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.