Surface Immobilization of PSI Using Vitamin K1-Like Molecular Wires for Fabrication of a Bio-Photoelectrode

We present a bio-photoelectrode made of photosystem I complex (PSI) of cyanobacteria, Thermosynechococcus elongatus, and molecular wires. The newly designed and synthesized molecular wire similar to vitamin K1 (VK1) has a naphthoquinone moiety that can connect to PSI, and a terpyridine moiety for connection to a Co(II) ion. Surface immobilization of PSI and molecular wires was performed by a self-assembled monolayer (SAM) formation process at indium tin oxide (ITO) followed by stepwise coordination reactions. The PSI-immobilized ITO showed a photocurrent action spectrum, whose profile was consistent with that of PSI. We have demonstrated a new method for the immobilization of PSI on the electrode surface, useful in the construction of phovoltaic cells or photon-sensing devices.