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Casanova-Moreno J, Bizzotto D. A Method for Determining the Actual Rate of Orientation Switching of DNA Self-Assembled Monolayers Using Optical and Electrochemical Frequency Response Analysis. Anal Chem 2015; 87:2255-63. [DOI: 10.1021/ac503919a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- J. Casanova-Moreno
- Department
of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
- Advanced
Materials and Process Engineering Laboratory, University of British Columbia, 2355 East Mall, Vancouver, BC V6T 1Z4, Canada
| | - D. Bizzotto
- Department
of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
- Advanced
Materials and Process Engineering Laboratory, University of British Columbia, 2355 East Mall, Vancouver, BC V6T 1Z4, Canada
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Ohtsuka T, Sasaki Y, Hyono A. AC Potential Modulation Reflectance of Iron Electrode Covered by Thin Passive Oxide. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2014.03.117] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Han X, Mendes SB. Optical impedance spectroscopy with single-mode electro-active-integrated optical waveguides. Anal Chem 2014; 86:1468-77. [PMID: 24417718 PMCID: PMC3983008 DOI: 10.1021/ac4030736] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An optical impedance spectroscopy (OIS) technique based on a single-mode electro-active-integrated optical waveguide (EA-IOW) was developed to investigate electron-transfer processes of redox adsorbates. A highly sensitive single-mode EA-IOW device was used to optically follow the time-dependent faradaic current originated from a submonolayer of cytochrome c undergoing redox exchanges driven by a harmonic modulation of the electric potential at several dc bias potentials and at several frequencies. To properly retrieve the faradaic current density from the ac-modulated optical signal, we introduce here a mathematical formalism that (i) accounts for intrinsic changes that invariably occur in the optical baseline of the EA-IOW device during potential modulation and (ii) provides accurate results for the electro-chemical parameters. We are able to optically reconstruct the faradaic current density profile against the dc bias potential in the working electrode, identify the formal potential, and determine the energy-width of the electron-transfer process. In addition, by combining the optically reconstructed faradaic signal with simple electrical measurements of impedance across the whole electrochemical cell and the capacitance of the electric double-layer, we are able to determine the time-constant connected to the redox reaction of the adsorbed protein assembly. For cytochrome c directly immobilized onto the indium tin oxide (ITO) surface, we measured a reaction rate constant of 26.5 s(-1). Finally, we calculate the charge-transfer resistance and pseudocapacitance associated with the electron-transfer process and show that the frequency dependence of the redox reaction of the protein submonolayer follows as expected the electrical equivalent of an RC-series admittance diagram. Above all, we show here that OIS with single-mode EA-IOW's provide strong analytical signals that can be readily monitored even for small surface-densities of species involved in the redox process (e.g., fmol/cm(2), 0.1% of a full protein monolayer). This experimental approach, when combined with the analytical formalism described here, brings additional sensitivity, accuracy, and simplicity to electro-chemical analysis and is expected to become a useful tool in investigations of redox processes.
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Affiliation(s)
- Xue Han
- Department of Physics and Astronomy, University of Louisville , Louisville, Kentucky 40292, United States
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Silva JF, Pavez J, Silva CP, Zagal JH. Electrocatalytic actvity of modified gold electrodes based on self-assembled monolayers of 4-mercaptopyridine and 4-aminothiophenol on Au(111) surfaces chemically functionalized with substituted and unsubstituted iron phthalocyanines. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.10.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Arikuma Y, Nakayama H, Morita T, Kimura S. Ultra-long-range electron transfer through a self-assembled monolayer on gold composed of 120-Å-long α-helices. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:1530-1535. [PMID: 21090665 DOI: 10.1021/la103882r] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Electron transfer through α-helices has attracted much attention from the viewpoints of their contributions to efficient long-range electron transfer occurring in biological systems and their utility as molecular-electronics elements. In this study, we synthesized a long 80mer helical peptide carrying a redox-active ferrocene unit at the terminal and immobilized the helical peptide on a gold surface. The molecular length is calculated to be 134 Å, in which the helix accounts for 120 Å. The preparation conditions of the self-assembled monolayers were intentionally changed to obtain monolayers with different physical states to study the correlation between molecular motions and electron transfer. Ellipsometry and infrared spectroscopy showed that the helical peptide forms a self-assembled monolayer with vertical orientation. Electrochemical measurements revealed that an electron is transferred from the ferrocene unit to gold through the monolayer composed of this long helical peptide, and the experimental data are well explained by theoretical results calculated under the assumption that electron transfer occurs by a unique hopping mechanism with the amide groups as hopping sites. Furthermore, we have observed a unique dependence of electron transfer on the monolayer packing, suggesting the importance of structural fluctuations of peptides on the electron transfer controlled by the hopping mechanism.
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Affiliation(s)
- Yoko Arikuma
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto, Japan
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Arikuma Y, Takeda K, Morita T, Ohmae M, Kimura S. Linker Effects on Monolayer Formation and Long-Range Electron Transfer in Helical Peptide Monolayers. J Phys Chem B 2009; 113:6256-66. [DOI: 10.1021/jp810200x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yoko Arikuma
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Kazuki Takeda
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Tomoyuki Morita
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Masashi Ohmae
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Shunsaku Kimura
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
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Okamoto S, Morita T, Kimura S. Electron transfer through a self-assembled monolayer of a double-helix peptide with linking the terminals by ferrocene. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:3297-3304. [PMID: 19437730 DOI: 10.1021/la8034962] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A unique molecular structure, a double-helix peptide, was self-assembled on gold, and the electron transfer through the monolayer was studied. The double-helix peptide consists of two 9mer 3(10)-helical peptide chains having a disulfide group at each N terminal and being linked by a ferrocene dicarboxylic acid between the C terminals. Each helical peptide chain has three naphthyl groups in a linear arrangement along the helix. The monolayer properties and the electron transfer from the ferrocene unit to gold were studied with reference peptides with a similar double helix but without naphthyl groups, a single helix with a dicarboxylic ferrocene unit, and a single helix with a monocarboxylic ferrocene unit. It was demonstrated that the naphthyl groups on the side chains had no effect on electron transfer, and the electron-transfer rate in the double-helix monolayer was not promoted, despite the two electron pathways in the molecule. We propose that in the double-helix monolayer, molecular motions are suppressed, possibly by its rigid structure tethered by the two linkers on gold to cancel out acceleration effects of the 2-fold electron pathways and the ferrocene substitution number. The factors that affect the electron-transfer reaction across the helical peptide SAMs are discussed in depth.
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Affiliation(s)
- Shinpei Okamoto
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
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MORITA T, WATANABE J, TAKEDA K, KAI M, ARIKUMA Y, OKAMOTO S, KIMURA S. Long-Range Electron Transfer through Self-Assembled Monolayers Composed of Helical Peptides Carrying a Ferrocene Unit at the Terminal. KOBUNSHI RONBUNSHU 2009. [DOI: 10.1295/koron.66.406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Takeda K, Morita T, Kimura S. Effects of Monolayer Structures on Long-Range Electron Transfer in Helical Peptide Monolayer. J Phys Chem B 2008; 112:12840-50. [DOI: 10.1021/jp805711v] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Kazuki Takeda
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Tomoyuki Morita
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Shunsaku Kimura
- Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
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Sagara T. UV‐Visible Reflectance Spectroscopy of Thin Organic Films at Electrode Surfaces. ACTA ACUST UNITED AC 2008. [DOI: 10.1002/9783527616817.ch2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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12
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Kai M, Takeda K, Morita T, Kimura S. Distance dependence of long-range electron transfer through helical peptides. J Pept Sci 2007; 14:192-202. [DOI: 10.1002/psc.974] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Fromondi I, Scherson DA. Oxidation of adsorbed CO on Pt(111) in CO-saturated perchloric acid aqueous solutions: simultaneous in situ time-resolved reflectance spectroscopy and second harmonic generation studies. J Phys Chem B 2007; 110:20749-51. [PMID: 17048880 DOI: 10.1021/jp0653095] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Simultaneous normalized differential reflectance spectroscopy (DeltaR/R) and second harmonic generation (SHG) has been employed to follow, independently, OH and adsorbed CO (CO(ads)) on a single Pt(111) microfacet in CO-saturated aqueous perchloric acidic solutions during voltammetric cycles, leading to the oxidation of CO(ads) and subsequent readsorption of CO on the surface. The results obtained are consistent with the disruption of the radical19 x radical19R19.1 degrees phase just prior to the oxidation of adsorbed CO.
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Suemori Y, Nagata M, Kondo M, Ishigure S, Dewa T, Ohtsuka T, Nango M. Phospholipid-linked quinones-mediated electron transfer on an electrode modified with lipid bilayers. Colloids Surf B Biointerfaces 2007; 61:106-12. [PMID: 17681456 DOI: 10.1016/j.colsurfb.2007.06.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2007] [Revised: 06/13/2007] [Indexed: 11/25/2022]
Abstract
Phospholipid-linked naphthoquinones separated by spacer methylene groups (C(n)), PE-C(n)-NQ (n=0, 5, 11), were synthesized to investigate the quinone-mediated electron transfers on a glassy carbon (GC) electrode covered with phospholipids membrane. The PE-C(n)-NQ could be incorporated in lipid bilayer composed of phosphatidylcholine and exhibited characteristic absorption spectral change corresponding to their redox state, quinone/hydroquinone. The cyclic voltammogram of PE-C(n)-NQ-containing lipid bilayer modified on a GC electrode indicated a set of waves corresponding to the consecutive two-electron and two-proton transfer reduction of the quinone moiety. The peak currents of PE-C(n)-NQ as a function of temperature showed a sharp break point in the current-temperature behavior, reflecting the gel-fluid phase transition. The shape of the cyclic voltammograms changed with the pH of the buffer solution. Below pH 6 the first step of the reduction of quinone was a monoprotonation of quinone, whereas above pH 10 the first step of the oxidation was a monodeprotonation of hydroquinone. This indicates that reaction sequences of quinone/hydroquinone were different with the change of the pH. These results showed that the PE-C(n)-NQ exhibited electron transfer associated with proton transfer in the lipid membranes, depending on the diffusivity of the redox species in the membrane and pH. Interestingly, less effect of the number of methylene of the spacer group on the peak currents was observed. Comparison of manganese porphyrin-mediated electron transfer that depends on the spacer methylene lengths [M. Nango, T. Hikita, T. Nakano, T. Yamada, M. Nagata, Y. Kurono, T. Ohtsuka, Langmuir 14 (1998) 407] is made.
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Affiliation(s)
- Yoshiharu Suemori
- Tsukuri College, Department of Applied Chemistry, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Japan
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Shi P, Fromondi I, Scherson DA. In situ, time-resolved reflectance spectroscopy in the microsecond domain: oxidation of adsorbed carbon monoxide on polycrystalline pt microelectrodes in aqueous solutions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:10389-98. [PMID: 17129007 DOI: 10.1021/la061497e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The dynamics of the electrooxidation of adsorbed CO, COads, on polycrystalline Pt microelectrodes has been examined in CO-saturated 0.5 M H2SO4 and 0.5 M HClO4 aqueous solutions, using in situ, time-resolved, normalized differential reflectance spectroscopy lambda = 633 nm). Attention was focused on the unique dependence of COads oxidation on the potential at which the adsorbed full CO monolayer is assembled (i.e., hydrogen adsorption/desorption vs the double-layer region) using both fast linear scan voltammetry and potential step techniques. As evidenced from the data collected, COads oxidation at a fixed potential proceeds at slower rates when the monolayer is formed in the double- layer region compared to when it is formed in the hydrogen adsorption/desorption region. Possible explanations for this effect are discussed.
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Affiliation(s)
- Ping Shi
- Department of Chemistry, Case Western Reserve University, Cleveland, Ohio 44106-7078, USA
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Doherty WJ, Wysocki RJ, Armstrong NR, Saavedra SS. Potential-Modulated, Attenuated Total Reflectance Spectroscopy of Poly(3,4-ethylenedioxythiophene) and Poly(3,4-ethylenedioxythiophene Methanol) Copolymer Films on Indium−Tin Oxide. J Phys Chem B 2006; 110:4900-7. [PMID: 16526729 DOI: 10.1021/jp056230n] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the first application of a potential-modulated spectroelectrochemical ATR (PM-ATR) instrument utilizing multiple internal reflections at an optically transparent electrode to study the charge-transfer kinetics and electrochromic response of adsorbed films. A sinusoidally modulated potential waveform was applied to an indium-tin oxide (ITO) electrode while simultaneously monitoring the optical reflectivity of thin (2-6 equivalent monolayers) copolymer films of poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-ethylenedioxythiophene methanol) (PEDTM), previously characterized in our laboratory. At high modulation frequencies the measured response of the polymer film is selective toward the fastest electrochromic processes in the film, presumably those occurring within the first adsorbed monolayer. Quantitative determination of the electrochromic switching rate, derived from the frequency response of the attenuated reflectivity, shows a linear decrease in the rate, from 11 x 10(3) s(-1) to 3 x 10(3) s(-1), with increasing proportions of PEDTM in the copolymer, suggesting that interactions between the methanol substituent on EDTM and the ITO surface slow the switching process by limiting the rate of conformational change in the polymer film.
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Affiliation(s)
- Walter J Doherty
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA
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Beghidja C, Wesolek M, Welter R. New manganese complexes with 2-salicyloylhydrazono-1,3-dithiolane ligand and various coordination solvents. Inorganica Chim Acta 2005. [DOI: 10.1016/j.ica.2005.06.037] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Viana A, Leupold S, Montforts FP, Abrantes L. Self-assembled monolayers of a disulphide-derivatised cobalt-porphyrin on gold. Electrochim Acta 2005. [DOI: 10.1016/j.electacta.2004.11.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Imahori H, Mori Y, Matano Y. Nanostructured artificial photosynthesis. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2003. [DOI: 10.1016/s1389-5567(03)00004-2] [Citation(s) in RCA: 320] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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