We report on an entirely man-made nano-bio architecture fabricated through noncovalent assembly of a cell-free expressed transmembrane proton pump and TiO2 semiconductor nanoparticles as an efficient nanophotocatalyst for H2 evolution. The system produces hydrogen at a turnover of about 240 μmol of H2 (μmol protein)-1 h-1 and 17.74 mmol of H2 (μmol protein)-1 h-1 under monochromatic green and white light, respectively, at ambient conditions, in water at neutral pH and room temperature, with methanol as a sacrificial electron donor. Robustness and flexibility of this approach allow for systemic manipulation at the nanoparticle-bio interface toward directed evolution of energy transformation materials and artificial systems.
Keywords: cell-free expression; hydrogen; nanodisc TiO2 nanoparticles; noncovalent assembly; proton pump; purple membranes; solar-to-fuel energy conversion.