title: Functional interfacing of Rhodospirillum rubrum chromatophores to a conducting support for capture and conversion of solar energy.
abstract: Owing to the considerable current interest in replacing fossil fuels with solar radiation as a clean, renewable, and secure energy source, light-driven electron transport in natural photosynthetic systems offers a valuable blueprint for conversion of sunlight to useful energy forms. In particular, intracytoplasmic membrane vesicles (chromatophores) from the purple bacterium Rhodospirillum rubrum provide a fully functional and robust photosynthetic apparatus, ideal for biophysical investigations of energy transduction and incorporation into biohybrid photoelectrochemical devices. These vesicular organelles, which arise by invagination of the cytoplasmic membrane, are the sites of the photochemical reaction centers and the light harvesting 1 (LH1) complex. The LH1 protein is responsible for collecting visible and near-IR radiant energy and funneling these excitations to the reaction center for conversion into a transmembrane charge separation. Here, we have investigated the morphology, fluorescence kinetics and photocurrent generation of chromatophores from Rsp. rubrum deposited directly onto gold surfaces in the absence of chemical surface modifications. Atomic force microscopy showed a significant coverage of the gold electrode surface by Rsp. rubrum chromatophores. By in situ fluorescence induction/relaxation measurements, a high retention of the quantum yield of photochemistry was demonstrated in the photoactive films. Chronoamperometric measurements showed that the assembled bioelectrodes were capable of generating sustained photocurrent under white light illumination at 220 mW/cm(2) with a maximum current of 1.5 μA/cm(2), which slowly declines in about 1 week. This study demonstrates the possibility of photoelectrochemical control of robust chromatophore preparations from Rsp. rubrum that paves the way for future incorporation into functional solar cells.
authors.affiliation: Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey , 610 Taylor Road, Piscataway, New Jersey 08854, United States.
authors.forename: John W
authors.initials: JW
authors.lastname: Harrold
authors.forename: Kamil
authors.initials: K
authors.lastname: Woronowicz
authors.forename: Joana L
authors.initials: JL
authors.lastname: Lamptey
authors.forename: John
authors.initials: J
authors.lastname: Awong
authors.forename: James
authors.initials: J
authors.lastname: Baird
authors.forename: Amir
authors.initials: A
authors.lastname: Moshar
authors.forename: Michele
authors.initials: M
authors.lastname: Vittadello
authors.forename: Paul G
authors.initials: PG
authors.lastname: Falkowski
authors.forename: Robert A
authors.initials: RA
authors.lastname: Niederman
mesh_terms: D020130:Bacterial Chromatophores / Q000737:chemistry* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D045304:Cytochromes c / Q000737:chemistry; D055664:Electrochemical Techniques; D004566:Electrodes; D006046:Gold / Q000737:chemistry; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry / Q000378:metabolism; D018625:Microscopy, Atomic Force; D011789:Quantum Theory; D012247:Rhodospirillum rubrum / Q000378:metabolism*; D012993:Solar Energy; D013050:Spectrometry, Fluorescence
chemical_list: D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; D006046:Gold; D045304:Cytochromes c