Nanostructured carbon fiber disk electrodes for sensitive determinations of adenosine and uric acid

Nanostructured carbon fiber microdisk electrodes were prepared by a combina tion of mechanical polishing and electrolytic treatment, where the latter i nvolved moderate oxidation of the surface, followed by a reduction, A high density of surface defects contributed to a high capacitance of the nanostr uctured electrodes. Facilitated proton transfer was observed at the nanostr uctured surface and was associated with cation-exchanged oxide defects. The nanostructured surfaces intercalated uric acid and adenosine and engaged i n fast electron/proton transfer in the oxidation of both analytes. As a res ult, electrolytic treatment followed by fast-scan voltammetry determination s led to a sensitive response to both analytes in physiological buffers. Th e nanostructured electrodes showed remarkable stability and could be easily regenerated and reused. With long use, electrode activity decreased, kinet ic discrimination of the surface-mediated reaction of ascorbate was achieve d at high scan rates.