Electrochemical Quartz Crystal Microbalance Study of Direct Bioelectrocatalytic Reduction of Bilirubin Oxidase

Adsorption behavior of bilirubin oxidase (BOD) on Au electrodes was studied using quartz crystal microbalance (QCM) measurements and electrochemical measurements of BOD-catalyzed reduction current of O2 without mediators. The QCM measurements supported the monolayer adsorption of BOD on Au electrodes at pH 5 to 9. The catalytic current density was, however, much smaller than that at hydrophilic edge plane-type carbon electrodes or than the calculated value for active BOD. Some denaturation is suggested on Au electrodes, which was supported by electrochemical QCM (EQCM) measurements.