Unusual long-term stability of enzymatic bioelectrocatalysis in organic solvents

• Published in: Journal of catalysis 2023-12, Vol.428, p.115163, Article 115163
• Main Authors: Bichon, Sabrina, Staigre, Priscilla, Gounel, Sébastien, Safarik, Tatjana, Carucci, Cristina, Kuhn, Alexander, Mano, Nicolas
• Format: Article
• Language: English
• Subjects: Bilirubin oxidase; Biocathode; Bioelectrosynthesis; Biofuel cell; Catalysis; Chemical Sciences; Material chemistry; O2 reduction; Organic tolerant enzyme; Porous electrodes; Redox hydrogel
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2023.115163

[Display omitted] •Highest stability reported so far for an enzymatic electrode in organic solvents.•It results from the combination of an engineered solvent tolerant enzyme, fine tune redox polymers and porous electrodes.•The half-life is as high as 8 days in 12.5 M methanol.•This approach could be generalized to others enzymatic systems. Organic solvent tolerant enzymes are of tremendous importance for the pharmaceutical industry in search of high added-value chemicals. However, enzymes exhibit usually weak long-term activity and stability in various media. Here, we report a general strategy allowing stabilizing and keeping enzymes active in mixed-solvent systems upon immobilization on an electrode surface. It consists in the combination of an engineered solvent-tolerant enzyme, combined with fine-tuned osmium-based redox polymers where the concentration of osmium complex has been specifically tuned to minimize its deswelling, associated with the use of porous gold electrodes. This approach is validated with bilirubin oxidase as a model system. This copper enzyme is able to oxidize a wide range of substrates, combined with the reduction of O2 to water. While all other enzymatic systems irreversibly lose their activity and stability in the presence of 7.5 M methanol or below, this optimized enzymatic system stays functional in 12.5 M methanol with no loss in current density. It exhibits a half-life of more than 8 days, which is unprecedented in the literature. We show that this electrode can also operate in DMSO, dioxane, acetonitrile and acetone, thus opening up a very wide variety of applications in the field of bioelectrocatalysis and bioelectrosynthesis.