Artificial Photosynthetic Hydrogel Microspheres Enable Programmable CO 2 Valorization

Converting carbon dioxide (CO2) into glucose, myo-inositol, sucrose, starch and other valuable products has been considered an achievable process mainly through plant photosynthesis. Combining photocatalysts with carbon-fixing microorganisms faces challenges, including incompatible reaction environments, light-induced microbial damage and inefficient connections between upstream carbon fixation and downstream product synthesis.

In a study published in Journal of the American Chemical Society, a team led by Profs. WANG Bo and YU Tao from the Shenzhen Institute of Advanced Technology of the Chinese Academy of Sciences developed an artificial photosynthetic hydrogel microsphere (APHM) which integrates photocatalysis, microbial CO2 fixation and downstream biotransformation within a single platform, providing a new route for programmable CO2 valorization.

Researchers developed a double-network hydrogel microsphere. The photocatalyst COF/Pt/Cr2O3 was embedded in the outer shell, while a carbonized melamine foam formed the inner core containing the carbon-fixing bacterium Acetobacterium woodii. The carbonized core blocked more than 99% of UV-visible light while remaining permeable to gases and nutrients, effectively protecting the microorganisms under intense illumination.

Besides, the APHM system used hydrogen as a short-range electron carrier and acetate as a chemical bridge between the upstream and downstream modules. In a 10-day continuous illumination experiment, this system achieved a H2-to-acetate conversion efficiency of 88.85%, significantly higher than the 7.9% of the non-compartmentalized control.

More importantly, acetate served as a versatile metabolic intermediate. Engineered Saccharomyces cerevisiae strains successfully converted APHM-derived acetate into glucose, myo-inositol, sucrose and starch, demonstrating the platform's flexibility for multi-product biomanufacturing.

This work presents a universal, efficient route to versatile solar-to-chemical synthesis. In the future, researchers will explore the design of efficient microbial-compatible hybrid systems and optimize the system's energy efficiency and sustainability.