Fabrication and characterization of nanoporous gold on microelectrode

•Nanoporous gold is formed on microelectrode by simple electrochemical treatment.•Bare gold microelectrodes are treated by oxidation reduction cycles in acidic media.•Large double-layer capacitance is observed in the voltammogram.•Surface area is 27 times higher than that of the bare electrode (Rf = 49).

We fabricated nanoporous gold (NPG) on a microelectrode by oxidization and reduction cycles (ORCs) in acidic media. The typical morphology of the nanostructures comprised tangled thickets of branched nanowires with diameters of 20-30 nm. Furthermore, the surface area was significantly increased compared with the bare electrode. The roughness factor (Rf) of NPG could be controlled by changing the number of ORCs. The NPG-modified microelectrode with a roughness factor of 49 could immobilize 11 times more thiol-modified oligodeoxynucleotides on its surface than a microelectrode without NPG (Rf = 1.8). The results suggest that NPG formation is an important method for enhancing the electrochemical sensitivity of microelectrodes.

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