Bioelectronic Photocommutator to Regulate Extracellular Electron Transfer Circuits for Microbial Photovoltaic Energy Storage.

Precise control over bioelectronic circuits is crucial for advancing bioelectrochemical systems, yet achieving dynamic, external regulation of electron flow has remained a fundamental challenge. Here, we create a biotic-abiotic hybrid system where the biosynthesized cadmium sulfide quantum dots (CdS QDs) are interfaced with the extracellular electron transfer (EET) pathway of Shewanella oneidensis MR-1, forming a bioelectronic photocommutator. This biotic-abiotic hybrid enables light-dependent, bidirectional control of electron transfer. Under 405 nm illumination, the system enhances outward EET, while switching to inward electron flow under 450 nm illumination. We elucidate the switching mechanism through photoelectrochemical, spectroscopic, XPS, and electrochemiluminescence experiments, revealing that the connection between CdS and EET proteins regulates the energy band structure of CdS via defect-state passivation, thus establishing two distinct electron transfer circuits. This switching mechanisim allows the QD-protein nanohybrid to function as the photocommutator on microbial electron transport pathway. Based on this principle, we have constructed a bioelectrochemical system, the microbial photovoltaic cell (MPC), that can be charged and discharged with light, and further demonstrated its application as a thin-film, flexible power source. This work provides a nano-bio interface for the active regulation of bioelectrochemical processes, opening an avenue for programmable biotic-abiotic nanohybrids in bioenergy storage and bioelectronics.