Clostridium butyricum mineralization of intracellular gold nanoclusters to boost biohydrogen production using visible light

Photocatalytic intracellular biohybrid systems hold great potential for enhancing biohydrogen production using solar energy. yet conventional approaches face nanoparticle toxicity and inefficient transmembrane electron transfer. Here, we developed an intracellular biohybrid system via in-situ biomineralization of gold nanoclusters (Au NCs, 2.15 ± 0.68 nm) within C. butyricum . This biosynthesis leveraged native ion-transport proteins for Au(III) uptake, synthesizing photocatalytically active Au NCs through cysteine-mediated reduction. This intracellular engineering confines photoexcitation and electron transfer within bacterial cells, eliminating transmembrane energy losses. As expected, the photoexcited Au NCs significantly enhanced intracellular NADH regeneration and ATP synthesis versus dark controls, boosting metabolic reducing power and energy. This resulted in a 70.42% increase in hydrogen production (2.34 mol H 2 ·mol -1 glucose). Furthermore, Au NCs eliminated reactive oxygen species (ROS), improving system viability and stability under visible light. This work establishes a platform for engineering biocompatible hybrid systems via endogenous nanophotocatalyst self-assembly. Graphical abstractOur work demonstrates a C. butyricum -based biohybrid system that mineralizes intracellular gold nanoclusters, and this system achieves highly efficient solar-driven hydrogen production, showcasing a novel strategy for sustainable energy conversion. • Non-genetic mineralization of Au NCs via intracellular cysteines in C. butyricum. • Light-activated Au NCs boost intracellular NADH/ATP regeneration. • Light-activated Au NCs can scavenge intracellular reactive oxygen species. • The hydrogen yield of the light-driven biohybrid system is 2.34 mol H 2 ·mol -1 glu.