Revisiting Solar Energy Flow in Nanomaterial-Microorganism Hybrid Systems.

Nanomaterial-microorganism hybrid systems (NMHSs), integrating semiconductor nanomaterials with microorganisms, present a promising platform for broadband solar energy harvesting, high-efficiency carbon reduction, and sustainable chemical production. While studies underscore its potential in diverse solar-to-chemical energy conversions, prevailing NMHSs grapple with suboptimal energy conversion efficiency. Such limitations stem predominantly from an insufficient systematic exploration of the mechanisms dictating solar energy flow. This review provides a systematic overview of the notable advancements in this nascent field, with a particular focus on the discussion of three pivotal steps of energy flow: solar energy capture, cross-membrane energy transport, and energy conversion into chemicals. While key challenges faced in each stage are independently identified and discussed, viable solutions are correspondingly postulated. In view of the interplay of the three steps in affecting the overall efficiency of solar-to-chemical energy conversion, subsequent discussions thus take an integrative and systematic viewpoint to comprehend, analyze and improve the solar energy flow in the current NMHSs of different configurations, and highlighting the contemporary techniques that can be employed to investigate various aspects of energy flow within NMHSs. Finally, a concluding section summarizes opportunities for future research, providing a roadmap for the continued development and optimization of NMHSs.

A Self-Assembled MOF-Escherichia Coli Hybrid System for Light-Driven Fuels and Valuable Chemicals Synthesis.

The development of semi-artificial photosynthetic systems, which integrate metal-organic frameworks (MOFs) with industrial microbial cell factories for light-driven synthesis of fuels and valuable chemicals, represents a highly promising avenue for both research advancements and practical applications. In this study, an MOF (PCN-222) utilizing racemic-(4-carboxyphenyl) porphyrin and zirconium chloride (ZrCl4) as primary constituents is synthesized. Employing a self-assembly process, a hybrid system is constructed, integrating engineered Escherichia coli (E. coli) to investigate light-driven hydrogen and lysine production. These results demonstrate that the light-irradiated biohybrid system efficiently produce H2 with a quantum efficiency of 0.75% under full spectrum illumination, the elevated intracellular reducing power NADPH is also observed. By optimizing the conditions, the biohybrid system achieves a maximum lysine production of 18.25 mg L-1, surpassing that of pure bacteria by 332%. Further investigations into interfacial electron transfer mechanisms reveals that PCN-222 efficiently captures light and facilitates the transfer of photo-generated electrons into E. coli cells. It is proposed that the interfacial energy transfer process is mediated by riboflavin, with facilitation by secreted small organic acids acting as hole scavengers for PCN-222. This study establishes a crucial foundation for future research into the light-driven biomanufacturing using E. coli-based hybrid systems.