Extracellular electron transfer across bacterial cell membranes via a cytocompatible redox-active polymer

A redox-active phospholipid polymer with a phospholipid-mimicking structure (2-methacryloyloxyethyl phosphorylcholine; MPC) was synthesized to construct a biocompatible electron mediator between bacteria and an electrode. In this study, a copolymer of MPC and vinylferrocene [VF; poly(MPC-co-VF)] (PMF) is synthesized. When PMF is added to cultures of the bacterial species Escherichia coli (Gram negative) and Lactobacillus plantarum (Gram positive), which have different cell wall structures, a catalytic current mediated by PMF is observed. In addition, growth curves and live/dead assays indicate that PMF does not decrease metabolic activity or cell viability. These results indicate that PMF mediates extracellular electron transfer across bacterial cell membranes without associated cytotoxicity.