Enhanced Photocurrent Production by Photosystem I Multilayer Assemblies

Abstract

The long‐term success of photosynthetic organisms has resulted in their global superabundance, which is sustained by their widespread, continual mass‐production of the integral proteins that photocatalyze the chemical processes of natural photosynthesis. Here, a fast, general method to assemble multilayer films composed of one such photocatalytic protein complex, Photosystem I (PSI), onto a variety of substrates is reported. The resulting films, akin to the stacked thylakoid structures of leaves, consist of a protein matrix that is permeable to electrochemical mediators and contain a high concentration of photoelectrochemically active redox centers. These multilayer assemblies vastly outperform previously reported monolayer films of PSI in terms of photocurrent production when incorporated into an electrochemical system, and it is shown that these photocatalytic properties increase with the film thickness. These results demonstrate how the assembly of micron‐thick coatings of PSI on non‐biological substrates yields a biohybrid ensemble that manifests the photocatalytic activity of the film’s individual protein constituents, and represent significant progress toward affordable, biologically‐inspired renewable energy conversion platforms.

Photocurrent generation by recombinant allophycocyanin trimer multilayer on TiO2 electrode

“…1 confirmed our hypothesis that the immobilized selfassembled APC trimers on a sensitized photoanode formed a multilayer with a non-specific orientation, similar to the findings from earlier reports [15][16][17]. Moreover, the very similar fluorescence emission spectra from the APC trimer complexes in solution and on TiO 2 both exhibited a fluorescence emission maximum at 660 nm with a shoulder at around 640 nm (Fig.…”

“…2a); this demonstrated that the APC trimer complexes were not disassembled following the formation of the multilayer structure [9]. It is possible that electrostatic interactions, especially hydrogen bonds, which are strong noncovalent forces in biological systems through functional groups such as carbonyl, amide, or imidazole, especially in macromolecules, are responsible for the multilayer adsorption, as noted previously [5,15,18]. Previous reports suggested that photocurrent generation based on photoreaction center complexes (BR, PSI, and PSII) is a result of electron transfer and continuous re-reductions in solution, after charge separation originating from the initial photoexcitation [4,17,19].…”

Plasmon‐Enhanced Photocurrent of Photosynthetic Pigment Proteins on Nanoporous Silver

“…[39,46] Confocal fluorescence microscopy and lifetime measurements. The adsorption profile of RC-LH1 complexes on silver working electrodes was measured using a home-built confocal fluorescence microscope described elsewhere.…”

Functional Nanohybrid Materials from Photosynthetic Reaction Center Proteins

“…60% energy conversion efficiency make this biohybrid system promising for molecular electronic applications. Substantial increase in the photocurrent was demonstrated when multilayers of PS I are prepared on conducting substrate [82,83].…”