Improved direct electron transfer-type bioelectrocatalysis of bilirubin oxidase using porous gold electrodes

Porous gold (Au) electrodes prepared by anodization of Au electrodes in buffer solutions containing glucose were utilized as scaffolds for direct electron transfer (DET)-type bioelectrocatalysis of bilirubin oxidase (BOD). The three-dimensional porous structure appeared to promote DET-type bioelectrocatalysis of BOD. The current density of DET-type bioelectrocatalysis of BOD increased with the formation of a three-dimensional porous structure at the beginning of anodization; however, it showed saturation characteristics with a further increase in the non-Faradaic current. Moreover, the glucose concentration during anodization affected the activity of DET-type bioelectrocatalysis of BOD. Scanning electron microscopy of the prepared porous Au electrodes showed that the structure of the electrode surface depended on the glucose concentration. Achieving a pore size distribution suitable for substrate transport and enzyme orientation seemed to be dependent on the glucose concentration.