Photo‐Induced Electron Transfer Between Photosystem 2 via Cross‐linked Redox Hydrogels

Abstract

Photosystem 2 (PS2) that catalyses light driven water splitting in photosynthesis was wired to electrode surfaces via osmium-containing redox polymers based on poly(vinyl)imidazol. The redox polymer hydrogel worked as both immobilization matrix and electron acceptor for the enzyme. Upon illumination, the enzymatic reaction could be switched on and a catalytic current was observed at the electrode. The catalytic current is directly dependent on the intensity of light used for the excitation of PS2. A typical current density of 45 mA cm À2 at a light intensity of 2.65 mW cm À2 could be demonstrated with a significantly improved operational stability.

Integrated photosystem II-based photo-bioelectrochemical cells

“…Photoexcitation of the complex that mimicked the native PSII/Q A complex resulted in O 2 evolution with the generation of photocurrent. Similarly, the PSII was electrically contacted with electrode surfaces by its immobilization in polymer hydrogels consisting of the Os(II/III)-polypyridine complex as electron transfer relay units 43 . Electrical wiring of PSI with electrodes was demonstrated by the reconstitution of the native PSI, from which vitamin K 1 was excluded, onto a synthetic quinone acceptor linked to a functionalized electrode by electrostatic interactions 44 .…”

Photoelectrochemical cells based on photosynthetic systems: a review

“…4d) (Das, 2004;Sekar et al, 2014); the redox-active hydrogels (Badura et al, 2008); and fixation on CNTs by means of molecular binding reagents . Each of these techniques provides various beneficial properties, including increasing the electrode surface area, increasing the rate of electron transfer between the electrode and photobiocatalyst and/or orientation of specific enzymes on the electrode.…”

“…In many studies, the correct orientation of the photosystems on a gold electrode provides specific binding of a histidinetagged protein complex with Ni-NTA molecule anchored to a gold electrode (Noji et al, 2011;Das et al, 2004). Badura et al (2008) used the osmium-containing polymer of polyvinyl-imidazole as modified electrode which worked as an immobilization device and a mediator (Fig. 4b).…”

“…a) connection of PS2 through gold nanoparticle (GNP; Au) histidine tag with Ni-nitrilotriacetic acid (Ni-NTA) attached to the C-terminus of the CP47 protein (adapted from Noji et al, 2011). b) PS2 associated with an osmium redox polymer containing a mediator network (adapted from Badura et al, 2008). Osmium complexes are represented by gray circles.…”

“…come in contact with the surface of the electrode, or a mediator should carry out the electron transfer. In fact, it is difficult to achieve direct electron transfer from the PS2 to the electrode because the site of Pheo-PQ is localized deeply inside the PS2 (Badura et al, 2008).…”