Spontaneously N-Doped Conjugated Polyelectrolyte Coatings Accelerate Electron Uptake in Shewanella Oneidensis

Bioelectrochemical systems interconvert electrical and chemical energy using living microorganisms, but their efficiency remains limited by slow electron exchange across abiotic-biotic interfaces. Herein, a spontaneous n-doped water-dispersible conjugated polyelectrolyte (CPE), PNB, is developed. The CPE self-assembles on the surface of Shewanella oneidensis MR-1 to create biocompatible coatings that accelerate inward extracellular electron transfer. PNB is obtained via an aldol condensation reaction and is described by an acceptor-acceptor π-conjugated backbone bearing quaternary ammonium side chains. This molecular architecture enables stable n-doping in aqueous media and a broad reduction potential window. When integrated as a cathodic interlayer, PNB-S. oneidensis biohybrids exhibit a 14-fold enhancement in electron injection and a 4-fold increase in electro-driven succinate production, compared to unmodified cells. Single-cell electrochemical mapping confirms faster, more efficient per-cell electron influx. These findings demonstrate that n-type CPEs can bridge external electrodes with cellular metabolisms, opening a material-based route to high-performance bioelectronic and electrosynthetic systems. By enabling more facile charge transfer between synthetic semiconductors and living catalysts, this work establishes a soft materials-driven framework for designing electronically coupled microbial systems with potential to advance sustainable bioelectronic technologies.