Au disk nanoelectrode down to 3 nm in radius was developed by a facile and reliable method and successfully applied for monitoring single cell exocytotic dopamine release. After electrochemical etching in HCl solution, the fine etched Au wire was insulated by cathodic electrophoretic paint followed by coated with polyimide, which retracted from the tip end during curing to expose the Au nanosurface. By cyclic voltammetric scanning the above tip in 0.5 M KCl, geometrically well-defined Au disk nanoelectrodes with different dimensions can be reproducibly prepared. Scanning electron microscopy (SEM) and steady-state voltammetry were utilized to determine the size of nanoelectrodes. The results showed that the specific combination of electrophoretic paint and polyimide greatly improved the surface structure and the electron transfer reaction of the Au nanoelectrodes. The heterogeneous electron transfer rate constant (ko) for the oxidation of ferrocene and potassium hexachloroiridate (III) and for the reduction of potassium ferricyanide were calculated to be k�=8.67�3.34 cm s-1 and a=0.73�0.03 for ferrocene, k�=6.20�4.03 cm s-1 and a=0.66 �0.09 for IrCl63-, k�= 4.69�3.26 cm s-1 and a=0.74�0.06 for Fe(CN)63-. The nanoelectrodes with well-demonstrated analytical performance were further applied to amperometrically monitor dopamine release from single rat pheochromacytoma (PC12) cells and have shown enhance sensitivity compared with carbon fiber micro or nano electrodes as well as high spatial resolution.

Development of Au disk nanoelectrode for highly sensitive detection of dopamine release from single cell

248th National Meeting (2014)

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