Sustainable One-Pot Electrochemical Approach for Entrapment of Multi-Enzymes and Biocompatible Redox Mediator.

Enzyme immobilization is regarded as a key factor for their effective utilization in various fields such as biofuel production, wastewater treatment, and biosensors. Designing new electrodes with biocompatible support matrices is essential to improve the stability in bioelectrocatalysis. Modified carbon felt electrodes were prepared and tested as bioelectrocatalyst under mild conditions - aqueous media at room temperature and basically neutral pH. Co-immobilization of dehydrogenase enzymes and neutral red (NR) dye at carbon felt electrodes was successfully achieved during electropolymerization of pyrrole in a facile one-step approach. Neutral red was incorporated to operate as a redox mediator supporting efficient electron transfer to the enzymes' active sites. Electrodes modified with alcohol dehydrogenase (ADH) have been employed to reduce acetaldehyde to ethanol in a chronoamperometic setting with Faradaic efficiency (FE) of up to 33 %. By incorporating the cascade reaction with three enzymes - ADH, formate dehydrogenase, and formaldehyde dehydrogenase - an electroreduction sequence could be established to produce methanol from CO2 reaching a FE of 10 %. The proposed approach shows good stability. Together with the simple implementation and application, this process is promising for employment in enzymatic electrocatalysis.