Cytochrome c-coupled photosystem I and photosystem II (PSI/PSII) photo-bioelectrochemical cells

Photo-bioelectrochemical cells are devices that use biomolecule-modified electrodes for the conversion of solar light to electrical power. We present the construction of a layered assembly of the native photosynthetic reaction centers photosystem I (PSI) and photosystem II (PSII), crosslinked by polyvinyl pyridine/methyl pyridinium and cytochrome c (Cyt. c) that act as an electron transfer mediating layer. Electrostatic interactions and glutaric dialdehyde crosslinking of the protein layers stabilize the biomolecules on the electrodes. The irradiation of the PSII/Cyt. c/PSI-modified electrodes facilitates an electron transfer cascade, where photoexcited PSII leads to O-2 evolution and to the reduction of Cyt. c, with the concomitant ejection of electrons from PSI to the electrode, and the reduction of the P-700(+) sites by the reduced Cyt. c units.