Semiartificial Photosynthetic Nanoreactors for H Generation.

A relatively unexplored energy source in synthetic cells is transmembrane electron transport, which like proton and ion transport can be light driven. Here, synthetic cells, called nanoreactors, are engineered for compartmentalized, semiartificial photosynthetic H production by a [FeFe]-hydrogenase (Hase). Transmembrane electron transfer into the nanoreactor was enabled by MtrCAB, a multiheme transmembrane protein from MR-1. On illumination, graphitic nitrogen-doped carbon dots (g-N-CDs) outside the nanoreactor generated and delivered photoenergized electrons to MtrCAB, which transferred these electrons to encapsulated Hase without requiring redox mediators. Compartmentalized, light-driven H production was observed with a turnover frequency (TOF) of 467 ± 64 h determined in the first 2 h. Addition of the redox mediator methyl viologen (MV) increased TOF to 880 ± 154 h. We hypothesize that the energetically "uphill" electron transfer step from MtrCAB to Hase ultimately limits the catalytic rate. These nanoreactors provide a scaffold to compartmentalize redox half reactions in semiartificial photosynthesis and inform on the engineering of nanoparticle-microbe hybrid systems for solar-to-chemical conversion.