Programming Bio-Bio Electronic Interfaces for Light-Driven Interspecies Electron Transfer.

Living systems organize electron flow through continuous, spatially and energetically structured redox networks, whereas most synthetic light-driven bioelectronic platforms rely on abiotic materials to generate and inject electrons into cells, limiting selective coupling between living partners. Here, we report programmable living electronic interfaces that enable direct, light-driven interspecies electron transfer (IET) between two living microorganisms. A conformal poly(3,4-ethylenedioxythiophene) network integrated into the envelope of Synechococcus elongatus intercepts and relays photosynthetic electron flux, while supramolecular cucurbit[7]uril host-guest interactions program defined cell-cell assembly with engineered Escherichia coli. Redox-active mediators embedded within the interface establish energetically matched electron-transfer pathways across species boundaries. Redox-potential matching identifies neutral red as an optimal mediator, enabling selective delivery of photosynthetic electrons into E. coli with an IET efficiency of 83.7%, thereby enhancing light-driven biocatalysis. This work establishes an integrated bio-bio electronic architecture that embeds electronic conduction within living redox networks, defining a paradigm for constructing light-powered microbial consortia distinct from conventional abiotic-bio hybrid systems.