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A Decaheme Cytochrome as a Molecular Electron Conduit in Dye-Sensitized Photoanodes.

Hwang ET, Sheikh K, Orchard KL, Hojo D, Radu V, Lee CY, Ainsworth E, Lockwood C, Gross MA, Adschiri T, Reisner E, Butt JN, Jeuken LJ - Adv Funct Mater (2015)

Bottom Line: 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 TiO2 nanocrystals that are modified with a phosphonated bipyridine Ru(II) dye (RuP).The step-by-step construction of the MtrC/TiO2 system 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 TiO2 nanocrystals to the surface via the MtrC conduit.

View Article: PubMed Central - PubMed

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.

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 TiO2 nanocrystals to a decaheme protein, MtrC from Shewanella oneidensis MR-1, where the 10 hemes of MtrC form a ≈7-nm-long molecular wire between the TiO2 and 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 TiO2 nanocrystals that are modified with a phosphonated bipyridine Ru(II) dye (RuP). The step-by-step construction of the MtrC/TiO2 system 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 TiO2 nanocrystals to the surface via the MtrC conduit. In other words, in these TiO2/MtrC hybrid photodiodes, MtrC traps the conduction-band electrons from TiO2 before 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.

No MeSH data available.


Related in: MedlinePlus

Scheme of the ligand-exchange reaction on the surface of oleic-acid-modified TiO2 nanocrystals to produce DHBA-TiO2 nanocrystals.
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fig02: Scheme of the ligand-exchange reaction on the surface of oleic-acid-modified TiO2 nanocrystals to produce DHBA-TiO2 nanocrystals.

Mentions: The TiO2 nanocrystals used for constructing the hybrid system were prepared by a high temperature solvothermal synthesis method to yield highly crystalline, oleic acid-capped (hydrophobic) particles with narrow size distribution. The particles were then transferred to the aqueous phase via a two-step ligand-exchange procedure using methyl-3,4-dihydroxy benzoate (MDB), which is subsequently converted to 3,4-dihydroxybenzoic acid (DHBA, Figure2). This two-step ligand exchange was used instead of direct modification with DHBA since both carboxylate and catechol groups can bind to TiO2; therefore, the ester group of MDB was used as a protecting group to ensure that the carboxylate group of DHBA was orientated away from the surface, resulting in highly water-dispersible nanoparticles. No change in crystallinity or particle size occurred during ligand exchange (transmission electron microscopy (TEM), X-ray diffraction (XRD)).


A Decaheme Cytochrome as a Molecular Electron Conduit in Dye-Sensitized Photoanodes.

Hwang ET, Sheikh K, Orchard KL, Hojo D, Radu V, Lee CY, Ainsworth E, Lockwood C, Gross MA, Adschiri T, Reisner E, Butt JN, Jeuken LJ - Adv Funct Mater (2015)

Scheme of the ligand-exchange reaction on the surface of oleic-acid-modified TiO2 nanocrystals to produce DHBA-TiO2 nanocrystals.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493899&req=5

fig02: Scheme of the ligand-exchange reaction on the surface of oleic-acid-modified TiO2 nanocrystals to produce DHBA-TiO2 nanocrystals.
Mentions: The TiO2 nanocrystals used for constructing the hybrid system were prepared by a high temperature solvothermal synthesis method to yield highly crystalline, oleic acid-capped (hydrophobic) particles with narrow size distribution. The particles were then transferred to the aqueous phase via a two-step ligand-exchange procedure using methyl-3,4-dihydroxy benzoate (MDB), which is subsequently converted to 3,4-dihydroxybenzoic acid (DHBA, Figure2). This two-step ligand exchange was used instead of direct modification with DHBA since both carboxylate and catechol groups can bind to TiO2; therefore, the ester group of MDB was used as a protecting group to ensure that the carboxylate group of DHBA was orientated away from the surface, resulting in highly water-dispersible nanoparticles. No change in crystallinity or particle size occurred during ligand exchange (transmission electron microscopy (TEM), X-ray diffraction (XRD)).

Bottom Line: 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 TiO2 nanocrystals that are modified with a phosphonated bipyridine Ru(II) dye (RuP).The step-by-step construction of the MtrC/TiO2 system 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 TiO2 nanocrystals to the surface via the MtrC conduit.

View Article: PubMed Central - PubMed

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.

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 TiO2 nanocrystals to a decaheme protein, MtrC from Shewanella oneidensis MR-1, where the 10 hemes of MtrC form a ≈7-nm-long molecular wire between the TiO2 and 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 TiO2 nanocrystals that are modified with a phosphonated bipyridine Ru(II) dye (RuP). The step-by-step construction of the MtrC/TiO2 system 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 TiO2 nanocrystals to the surface via the MtrC conduit. In other words, in these TiO2/MtrC hybrid photodiodes, MtrC traps the conduction-band electrons from TiO2 before 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.

No MeSH data available.


Related in: MedlinePlus