Bacterial-Electrochemical Platform Utilizing a MXene-Peptide Hydrogel

Escherichia coli is a compelling target for bioelectrochemical engineering due to its exceptionally well-established capabilities for recombinant enzyme expression. Yet, a central limitation is the lack of stable and efficient electron delivery to intracellular enzymes, as E. coli lacks native extracellular electron uptake pathways. Thus, programmable intracellular catalysis can be realized, provided efficient electron delivery is achieved. Here, we demonstrate a strategy that supports sustained bioelectrochemical hydrogen (H₂) production by E. coli expressing a recombinant algal Ferredoxin-[FeFe]-hydrogenase fusion protein. Bacterial cells are immobilized within a self-assembling peptide hydrogel incorporating the conductive Ti₃C₂T_z MXene, forming a stable, electroactive biohybrid interface on carbon felt electrodes. The peptide-MXene hydrogel supports high and stable currents, sustained H₂ generation, and improved residual enzymatic activity during prolonged operation. Structural, mechanical, and metabolic analyses indicate that MXene reinforces the peptide matrix without compromising bacterial viability, enhancing electrode integrity and electronic coupling. Together, these results establish a proof of concept for a broadly applicable bioelectrochemical platform that enables electrode-microbe coupling in E. coli via a materials-based approach, thereby circumventing the need for genetically engineered exoelectrogenicity. This strategy enables electron delivery to non-native intracellular redox enzymes and provides a foundation for coupling electrochemical energy input to engineered metabolic pathways.