Radomski, JohannaJohannaRadomskiVieira Dessoy Maciel, LucianaLucianaVieira Dessoy MacielSieber, VolkerVolkerSieber2023-10-022023-10-022023https://publica.fraunhofer.de/handle/publica/45118210.1016/j.bioelechem.2023.1083982-s2.0-8514832606836805205The integration of redox enzymes on electrode surfaces enables the use of renewable energy for highly specific bioelectrochemical synthesis. Herein, we investigate the oxidation of glucose to gluconic acid on a bioanode, combining electrochemical and enzymatic components. Gluconic acid is a valuable chemical widely used in the industry. The bioanode consists of a redox hydrogel film of polyethylenimine (PEI) containing ferrocene (Fc) as a mediator, glycerol diglycidyl ether (GDGE) as a cross-linker, and the enzyme glucose oxidase (GOx). Optimization of the enzyme and cross-linker loading in the redox film led to faradaic efficiencies up to 96 ± 5 % for gluconate. The oxygen-free setup was highly stable for quantitative electrosynthesis, yielding gluconate concentrations of 6.4 ± 0.25 mmol L-1. Moreover, this catalase-free anaerobic system showed no production of H2O2 within 24 h, thereby eliminating the deactivation of the GOx caused by H2O2 and a high enzyme performance, with a turnover frequency (TOF) of 5 x10-3 s−1. This is the first quantitative bioelectrosynthesis of gluconate in an entirely anaerobic environment with electrode stability of at least 8 h.enBioanodesElectrochemical glucose oxidationGluconateHydrogelsRedox polymerjournal article