Photocurrent generation by photosystem 1 integrated in crosslinked redox hydrogels

Photosystem 1 (PS1) catalyzes the light driven translocation of electrons in the process of oxygenic photosynthesis. Isolated PS1 was immobilised on a gold electrode surface via an Os complex containing redox polymer hydrogel which simultaneously is used as immobilisation matrix and as electron donor for PS1. On addition of methyl viologen as sacrificial electron acceptor, a catalytic photocurrent with densities of up to 29 μA cm−2 at a light intensity of 1.8 mW cm−2 was observed upon illumination—equivalent to an incident photon to carrier efficiency (IPCE) of 3.1%. The strong dependence of the catalytic reaction on the light intensity and the dissolved oxygen concentration indicates that a significant photocurrent from excited PS1 to the electrode can only be realized in the presence of oxygen.