Photocurrent generation properties of Histag-photosystem II immobilized on nanostructured gold electrode

It is well known that photosystem II (PSII) can produce electrons, oxygen, and protons simultaneously via a water-splitting photoreaction. These photochemical properties are expected to exhibit photoconductive function for PSII. In the present study, we have first observed a stable photocurrent due to the photoexcitation of PSII and the subsequent water-splitting reaction, by successfully immobilizing PSII on the self-assembled monolayer (SAM) of a nickel-nitrilotriacetic acid complex (Ni-NTA) prepared on a gold surface via a polyhistidine tag (Histag) as a linker molecule. We have further succeeded in the fabrication of PSII-gold nanoparticle multistructures on the surface of gold electrode, and significant enhancement of photocurrents was achieved due to increased number of immobilized PSII.