Recent advances in surface chemistry of electrodes to promote direct enzymatic bioelectrocatalysis

Redox enzymes catalyze major reactions in microorganisms to supply energy for life. Their use in electrochemical biodevices requires their integration on electrodes, while maintaining their activity and optimizing their stability. In return, such applicative development puts forward the knowledge on involved catalytic mechanisms, providing a direct electrode connection of the enzyme is fulfilled. Enzymes being large molecules with active site embedded in an insulating moiety, direct bioelectrocatalysis supposes strategies for specific orientation of the enzyme to be developed. In this review, we summarize recent advances during the past 3 years in the chemical modification of electrodes favoring direct electrocatalysis. We present the different methodologies used according to the electrode materials, including metals, carbon-based electrodes, or porous structures and discuss the gained insights into bioelectrocatalysis. We especially focus on enzyme engineering, which appears as an emerging strategy for enzyme anchoring. Remaining challenges will be discussed with regard to these later findings. •Applicability of redox enzymes as electrocatalysts requires their oriented immobilization on electrodes.•Specific recognition of enzymes on related chemically modified electrodes favors DET.•Protein engineering to fit DET requirements is an increasing research area.•Electrode modification mainly involves diazonium salt grafting, SAMs, amine oxidation, or p–p stacking.•Grafting of enzymes includes maleimide, imine, or carbodimide coupling and click chemistry.