Conductive Polymers to ‘Wire’ the Microbial Electronics Interface

Organic waste streams contain a significant amount of latent energy that is difficult to harvest. Microbial electrochemical systems (MESs), which extract electrons through microbial metabolism, are a promising technology to recover this energy. Despite advances in these technologies, microbial electrocatalysis in MESs remains limited by inefficient electron transfer between living cells and electrodes. Here, we demonstrate significant improvement in this interfacial electron transfer through the incorporation of electron- and ion-conductive polymers. We have designed these polymers with a conductive backbone and side chains that mimic ligands of catalytic centers in redox-active enzymes. Specifically, methylimidazolium groups mimic protonated histidines prevalent in enzyme active sites. We show that these polymers substantially enhance mediated electron transfer and overall current generation by Shewanella oneidensis, an electroactive microbe often used in MESs. Our work highlights the importance of materials engineering applied to the biotic-abiotic interface to improve charge transfer in bioelectronic systems.