Fabrication and characterization of nanoporous gold on microelectrode

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 (R-f) 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 (R-f = 1.8). The results suggest that NPG formation is an important method for enhancing the electrochemical sensitivity of microelectrodes. (C) 2016 Elsevier B.V. All rights reserved.