title: A Decaheme Cytochrome as a Molecular Electron Conduit in Dye-Sensitized Photoanodes.
abstract: In nature, charge recombination in light-harvesting reaction centers is minimized by efficient charge separation. Here, it is aimed to mimic this by coupling dye-sensitized TiO2nanocrystals to a decaheme protein, MtrC fromShewanella oneidensisMR-1, where the 10 hemes of MtrC form a ≈7-nm-long molecular wire between the TiO2and the underlying electrode. The system is assembled by forming a densely packed MtrC film on an ultra-flat gold electrode, followed by the adsorption of approximately 7 nm TiO2nanocrystals that are modified with a phosphonated bipyridine Ru(II) dye (RuP). The step-by-step construction of the MtrC/TiO2system is monitored with (photo)electrochemistry, quartz-crystal microbalance with dissipation (QCM-D), and atomic force microscopy (AFM). Photocurrents are dependent on the redox state of the MtrC, confirming that electrons are transferred from the TiO2nanocrystals to the surface via the MtrC conduit. In other words, in these TiO2/MtrC hybrid photodiodes, MtrC traps the conduction-band electrons from TiO2before transferring them to the electrode, creating a photobioelectrochemical system in which a redox protein is used to mimic the efficient charge separation found in biological photosystems.
authors.affiliation: School of Biomedical Sciences, University of Leeds Leeds, LS2 9JT, UK E-mail: L.J.C.Jeuken@leeds.ac.uk ; The Astbury Centre for Structural Molecular Biology, University of Leeds Leeds, LS2 9JT, UK.
authors.forename: Ee Taek
authors.initials: ET
authors.lastname: Hwang
authors.affiliation: School of Biomedical Sciences, University of Leeds Leeds, LS2 9JT, UK E-mail: L.J.C.Jeuken@leeds.ac.uk ; The Astbury Centre for Structural Molecular Biology, University of Leeds Leeds, LS2 9JT, UK.
authors.forename: Khizar
authors.initials: K
authors.lastname: Sheikh
authors.affiliation: Department of Chemistry, University of Cambridge Lensfield Road, Cambridge, CB2 1EW, UK E-mail: Reisner@ch.cam.ac.uk ; Advanced Institute for Materials Research, Tohoku University 2-1-1 Katahira Aoba-ku Sendai, Miyagi, 980-8577, Japan E-mail: Hojo.Daisuke@wpi-aimr.tohoku.ac.jp.
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Orchard
authors.affiliation: Advanced Institute for Materials Research, Tohoku University 2-1-1 Katahira Aoba-ku Sendai, Miyagi, 980-8577, Japan E-mail: Hojo.Daisuke@wpi-aimr.tohoku.ac.jp.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hojo
authors.affiliation: School of Biomedical Sciences, University of Leeds Leeds, LS2 9JT, UK E-mail: L.J.C.Jeuken@leeds.ac.uk ; The Astbury Centre for Structural Molecular Biology, University of Leeds Leeds, LS2 9JT, UK.
authors.forename: Valentin
authors.initials: V
authors.lastname: Radu
authors.affiliation: Department of Chemistry, University of Cambridge Lensfield Road, Cambridge, CB2 1EW, UK E-mail: Reisner@ch.cam.ac.uk.
authors.forename: Chong-Yong
authors.initials: CY
authors.lastname: Lee
authors.affiliation: Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia Norwich Research Park, Norwich, NR4 7TJ, UK E-mail: J.Butt@uea.ac.uk.
authors.forename: Emma
authors.initials: E
authors.lastname: Ainsworth
authors.affiliation: Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia Norwich Research Park, Norwich, NR4 7TJ, UK E-mail: J.Butt@uea.ac.uk.
authors.forename: Colin
authors.initials: C
authors.lastname: Lockwood
authors.affiliation: Department of Chemistry, University of Cambridge Lensfield Road, Cambridge, CB2 1EW, UK E-mail: Reisner@ch.cam.ac.uk.
authors.forename: Manuela A
authors.initials: MA
authors.lastname: Gross
authors.affiliation: Advanced Institute for Materials Research, Tohoku University 2-1-1 Katahira Aoba-ku Sendai, Miyagi, 980-8577, Japan E-mail: Hojo.Daisuke@wpi-aimr.tohoku.ac.jp.
authors.forename: Tadafumi
authors.initials: T
authors.lastname: Adschiri
authors.affiliation: Department of Chemistry, University of Cambridge Lensfield Road, Cambridge, CB2 1EW, UK E-mail: Reisner@ch.cam.ac.uk.
authors.forename: Erwin
authors.initials: E
authors.lastname: Reisner
authors.affiliation: Centre for Molecular and Structural Biochemistry, School of Chemistry and School of Biological Sciences, University of East Anglia Norwich Research Park, Norwich, NR4 7TJ, UK E-mail: J.Butt@uea.ac.uk.
authors.forename: Julea N
authors.initials: JN
authors.lastname: Butt
authors.affiliation: School of Biomedical Sciences, University of Leeds Leeds, LS2 9JT, UK E-mail: L.J.C.Jeuken@leeds.ac.uk ; The Astbury Centre for Structural Molecular Biology, University of Leeds Leeds, LS2 9JT, UK.
authors.forename: Lars J C
authors.initials: LJ
authors.lastname: Jeuken
keywords: dye-sensitized nanoparticles; electron transfer; metalloprotein; photoelectrochemistry; protein-film electrochemistry