Photosystem II–Gold Nanoparticle Conjugate as a Nanodevice for the Development of Artificial Light-Driven Water-Splitting Systems

Abstract

Photosystem II (PSII) is an enzyme that performs efficient light-driven water oxidation to provide electrons necessary for CO2 fixation in photosynthesis. In this study, we have for the first time generated PSII–gold nanoparticle (GNP) conjugates dispersed in a solution aiming at applications in artificial photosynthesis. PSII core complexes from the thermophilic cyanobacterium Thermosynechococcus elongatus, in which a His-tag was introduced into the C-terminus of CP47, were immobilized on GNPs with a 20 nm diameter via nickel-nitrilotriacetic acid, orienting the electron acceptor side to the gold surface. Optical analysis showed that four to five PSII dimers are bound to a single GNP, which was confirmed by transmission electron microscopy. The PSII immobilized on GNP retained O2 evolution activity comparable to that of free PSII. The PSII–GNP conjugate will be a useful nanodevice for the development of artificial systems for light-driven water splitting into O2 and H2.