Size-controlled fabrication of gold nanodome arrays and its application to enzyme electrodes

Nanostructures of an electrode affect its functionality. We have developed a method for the fabrication of hexagonally ordered gold nanodome arrays with simple nanomorphology by employing the template-casting method. Templates with shallow concave shapes were fabricated using porous anodic aluminum oxide (AAO) and were then filled with gold. Scanning electron microscopy and atomic force microscopy images revealed that the morphology of the nanodomes was well controlled and uniformly shaped and had smooth hemispheres separated by steep valleys. Different anodization conditions gave different AAO interpore distances, enabling the generation of films having different cell diameters ranging over 27–109 nm. Furthermore, we confirmed that the gold nanodome arrays could function as electrodes for the direct electron transfer of cytochrome P450 immobilized on the electrode. This AAO-based electrode fabrication method provides functional electrodes, which are useful for studying the activation of redox enzymes and analyzing the functionality of nanostructures.