Chemoenzymatic reaction cascade in an All-in-One electrochemical system with in situ supply of H2O2 for biosynthesis in aqueous and organic media (AiO-eChemBIO) 

This project aims to develop a novel and optimizable platform for H2O2-dependent enzymatic reaction cascades in aqueous as well as organic media. A team of three researchers from different institutes at Hamburg University of Technology (TUHH) works together in an interdisciplinary team to establish a fully controllable electrochemical in situ H2O2 synthesis using a novel All-in-One (AiO) electrode, as well as to characterize and optimize enzyme immobilization on the electrode and two model biocatalytic reaction cascades. Hydrogen peroxide (H2O2) is a mild and stable oxidant that can easily be produced electrochemically and is already being used as a substrate in many biocatalytic processes. Its application in large-scale industrial processes however is limited by two factors: Firstly, H2O2 is produced in an aqueous solution by classical chemosynthesis, introducing water into organic systems and possibly favoring side reactions. Secondly, higher H2O2 concentrations result in a detrimental effect on the activity and stability of many enzymes. Therefore, the accurate and tuneable dosage of H2O2 into the reaction system is challenging, but of great importance.

In the proposed All-in-One (AiO) electrode setup the in situ production rate of H2O2 can be accurately tuned electrically to match the catalytic capacity of the enzymes present in the system. To further increase the proximity of the H2O2 production and consumption, the enzymes can be immobilized directly on the electrode producing the H2O2. This could potentially keep the H2O2 concentration low and reduce the detrimental effect of H2O2 on the activity and stability of the enzyme. The H2O2 is produced in situ for the biocatalytic step by electrochemical reduction of oxygen at the anode followed by conversion to H2O2 at the cathode. The AiO electrode consists of an inner chamber, where the oxygen is generated at the anode and passes through the cathode by a pressure gradient, where it is converted to H2O2. This is possible because the cathode is made out of a highly porous carbon foam backbone called Globugraphite, coated with carbon nanotubes (CNTs). Both materials show a high specific surface area and are tuneable in their micro-and macroscopic configuration layout, encompassing an increased potential for high H2O2 production rates as well as efficient enzyme immobilization. With its unique layout of the inner chamber and outlying gas diffusion cathode, the complete AiO electrode can be mounted into a reactor set up similarly to a pH or pO2 probe, making it applicable to a wide range of reactor setups and scale-up scenarios.

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Co-workers: f.l.t.r.: Hubert Beisch (IPC), Victoria Bueschler (ITB), Giovanni Sayoga (IBB).

Project overview