Rational Design of Enzyme-Modified Electrodes for Optimized Bioelectrocatalytic Activity

The immobilization of bilirubin oxidase (BOD) on macroporous gold electrodes for the optimization of bioelectrocatalytic activity is described. A bilirubin oxidase mutant S362C (cys-BOD) engineered with a cysteine residue located on purpose at the enzyme surface close to the T1 active center was used. It allows the attachment in one-step of a self-assembled monolayer of the enzyme to gold through a reaction between the thiol group of the cysteine residue and the metal surface. BOD immobilization of wild type and S362C mutant in macroporous gold electrodes allowed high retention of activity and perfect control of the overall BOD loading due to the fine-tuning of the macroporous structure. The macroporous arrangement together with the use of cys-BOD makes these rationally designed enzyme-modified electrodes very promising candidates for high-performance bioelectrocatalytic devices with improved activity and stability.