title: Self-organized photosynthetic nanoparticle for cell-free hydrogen production.
abstract: There is considerable interest in making use of solar energy through photosynthesis to create alternative forms of fuel. Here, we show that photosystem I from a thermophilic bacterium and cytochrome-c(6) can, in combination with a platinum catalyst, generate a stable supply of hydrogen in vitro upon illumination. The self-organized platinization of the photosystem I nanoparticles allows electron transport from sodium ascorbate to photosystem I via cytochrome-c(6) and finally to the platinum catalyst, where hydrogen gas is formed. Our system produces hydrogen at temperatures up to 55 degrees C and is temporally stable for >85 days with no decrease in hydrogen yield when tested intermittently. The maximum yield is approximately 5.5 micromol H(2) h(-1) mg(-1) chlorophyll and is estimated to be approximately 25-fold greater than current biomass-to-fuel strategies. Future work will further improve this yield by increasing the kinetics of electron transfer, extending the spectral response and replacing the platinum catalyst with a renewable hydrogenase.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors.forename: Ifeyinwa J
authors.initials: IJ
authors.lastname: Iwuchukwu
authors.forename: Michael
authors.initials: M
authors.lastname: Vaughn
authors.forename: Natalie
authors.initials: N
authors.lastname: Myers
authors.forename: Hugh
authors.initials: H
authors.lastname: O'Neill
authors.forename: Paul
authors.initials: P
authors.lastname: Frymier
authors.forename: Barry D
authors.initials: BD
authors.lastname: Bruce
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D001674:Bioelectric Energy Sources; D002384:Catalysis; D000458:Cyanobacteria / Q000737:chemistry / Q000378:metabolism*; D045365:Cytochromes c6 / Q000302:isolation & purification / Q000378:metabolism*; D006859:Hydrogen / Q000378:metabolism*; D008958:Models, Molecular; D053758:Nanoparticles / Q000737:chemistry; D045331:Photosystem I Protein Complex / Q000302:isolation & purification / Q000378:metabolism*; D010984:Platinum / Q000737:chemistry; D055550:Protein Stability; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D045365:Cytochromes c6; D045331:Photosystem I Protein Complex; D010984:Platinum; D006859:Hydrogen