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Chen N, Li S, Zhao P, Liu R, Xie Y, Lin JL, Nijhuis CA, Xu B, Zhang L, Xu H, Li Y. Extreme long-lifetime self-assembled monolayer for air-stable molecular junctions. SCIENCE ADVANCES 2023; 9:eadh3412. [PMID: 37851815 PMCID: PMC10584343 DOI: 10.1126/sciadv.adh3412] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Accepted: 09/14/2023] [Indexed: 10/20/2023]
Abstract
The molecular electronic devices based on self-assembled monolayer (SAM) on metal surfaces demonstrate novel electronic functions for device minimization yet are unable to realize in practical applications, due to their instability against oxidation of the sulfur-metal bond. This paper describes an alternative to the thiolate anchoring group to form stable SAMs on gold by selenides anchoring group. Because of the formation of strong selenium-gold bonds, these stable SAMs allow us to incorporate them in molecular tunnel junctions to yield extremely stable junctions for over 200 days. A detailed structural characterization supported by spectroscopy and first-principles modeling shows that the oxidation process is much slower with the selenium-gold bond than the sulfur-gold bond, and the selenium-gold bond is strong enough to avoid bond breaking even when it is eventually oxidized. This proof of concept demonstrates that the extraordinarily stable SAMs derived from selenides are useful for long-lived molecular electronic devices and can possibly become important in many air-stable applications involving SAMs.
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Affiliation(s)
- Ningyue Chen
- Key Laboratory of Organic Optoelectronics and Molecular Engineering and Laboratory of Flexible Electronics Technology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Shuwei Li
- Center for Combustion Energy, Tsinghua University, Beijing 100084, China
- School of Vehicle and Mobility, and State Key Laboratory of Intelligent Green Vehicle and Mobility, Tsinghua University, Beijing 100084, China
| | - Peng Zhao
- Key Laboratory of Organic Optoelectronics and Molecular Engineering and Laboratory of Flexible Electronics Technology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Ran Liu
- School of Electrical and Computer Engineering, University of Georgia, Athens, GA 30602, USA
| | - Yu Xie
- Key Laboratory of Organic Optoelectronics and Molecular Engineering and Laboratory of Flexible Electronics Technology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Jin-Liang Lin
- Key Laboratory of Organic Optoelectronics and Molecular Engineering and Laboratory of Flexible Electronics Technology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Christian A. Nijhuis
- Hybrid Materials for Opto-Electronics Group, Department of Molecules and Materials, MESA+ Institute for Nanotechnology, Molecules Centre and Centre for Brain-Inspired Nano Systems, Faculty of Science and Technology, University of Twente, 7500 AE Enschede, Netherlands
| | - Bingqian Xu
- School of Electrical and Computer Engineering, University of Georgia, Athens, GA 30602, USA
| | - Liang Zhang
- Center for Combustion Energy, Tsinghua University, Beijing 100084, China
- School of Vehicle and Mobility, and State Key Laboratory of Intelligent Green Vehicle and Mobility, Tsinghua University, Beijing 100084, China
| | - Huaping Xu
- Key Laboratory of Organic Optoelectronics and Molecular Engineering and Laboratory of Flexible Electronics Technology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Yuan Li
- Key Laboratory of Organic Optoelectronics and Molecular Engineering and Laboratory of Flexible Electronics Technology, Department of Chemistry, Tsinghua University, Beijing 100084, China
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Delley MF, Nichols EM, Mayer JM. Interfacial Acid-Base Equilibria and Electric Fields Concurrently Probed by In Situ Surface-Enhanced Infrared Spectroscopy. J Am Chem Soc 2021; 143:10778-10792. [PMID: 34253024 DOI: 10.1021/jacs.1c05419] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Understanding how applied potentials and electrolyte solution conditions affect interfacial proton (charge) transfers at electrode surfaces is critical for electrochemical technologies. Herein, we examine mixed self-assembled monolayers (SAMs) of 4-mercaptobenzoic acid (4-MBA) and 4-mercaptobenzonitrile (4-MBN) on gold using in situ surface-enhanced infrared absorption spectroscopy (SEIRAS). Measurements as a function of the applied potential, the electrolyte pD, and the electrolyte concentration determined both the relative surface populations of acidic and basic forms of 4-MBA, as well as the local electric fields at the SAM-solution interface by following the Stark shifts of 4-MBN. The effective acidity of the SAM varied with the applied potential, requiring a 600 mV change to move the pKa by one unit. Since this is ca. 10× the Nernstian value of 59 mV/pKa, ∼90% of the applied potential dropped across the SAM layer. This emphasizes the importance of distinguishing applied potentials from the potential experienced at the interface. We use the measured interfacial electric fields to estimate the experienced potential at the SAM edge. The SAM pKa showed a roughly Nernstian dependence on this estimated experienced potential. An analysis of the combined acid-base equilibria and Stark shifts reveals that the interfacial charge density has significant contributions from both SAM carboxylate headgroups and electrolyte components. Ion pairing and ion penetration into the SAM also influence the observed surface acidity. To our knowledge, this study is the first concurrent examination of both effective acidity and electric fields, and highlights the relevance of experienced potentials and specific ion effects at functionalized electrode surfaces.
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Affiliation(s)
- Murielle F Delley
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland.,Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - Eva M Nichols
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada.,Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
| | - James M Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
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Hengge E, Steyskal EM, Bachler R, Dennig A, Nidetzky B, Würschum R. Adsorption and desorption of self-assembled L-cysteine monolayers on nanoporous gold monitored by in situ resistometry. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2019; 10:2275-2279. [PMID: 31807412 PMCID: PMC6880825 DOI: 10.3762/bjnano.10.219] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 10/31/2019] [Indexed: 06/10/2023]
Abstract
Surface modifications of nanoporous metals have become a highly attractive research field as they exhibit great potential for various applications, especially in biotechnology. Using self-assembled monolayers is one of the most promising approaches to modify a gold surface. However, only few techniques are capable of characterizing the formation of these monolayers on porous substrates. Here, we present a method to in situ monitor the adsorption and desorption of self-assembled monolayers on nanoporous gold by resistometry, using cysteine as example. During the adsorption an overall relative change in resistance of 18% is detected, which occurs in three distinct stages. First, the cysteine molecules are adsorbed on the outer surface. In the second stage, they are adsorbed on the internal surfaces and in the last stage the reordering accompanied by additional adsorption takes place. The successful binding of cysteine on the Au surface was confirmed by cyclic voltammetry, which showed a significant decrease of the double-layer capacitance. Also, the electrochemically controlled desorption of cysteine was monitored by concomitant in situ resistometry. From the desorption peak related to the (111) surface of the structure, which is associated with a resistance change of 4.8%, an initial surface coverage of 0.48 monolayers of cysteine could be estimated.
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Affiliation(s)
- Elisabeth Hengge
- Insitute of Materials Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
| | - Eva-Maria Steyskal
- Insitute of Materials Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
| | - Rupert Bachler
- Insitute of Materials Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
| | - Alexander Dennig
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12, A-8010 Graz, Austria
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12, A-8010 Graz, Austria
| | - Roland Würschum
- Insitute of Materials Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
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Fies WA, Dugger JW, Dick JE, Wilder LM, Browning KL, Doucet M, Browning JF, Webb LJ. Direct Measurement of Water Permeation in Submerged Alkyl Thiol Self-Assembled Monolayers on Gold Surfaces Revealed by Neutron Reflectometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5647-5662. [PMID: 30919634 DOI: 10.1021/acs.langmuir.9b00541] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Self-assembled monolayers (SAMs) of alkyl thiols are frequently used to chemically functionalize gold surfaces for applications throughout materials chemistry, electrochemistry, and biotechnology. Despite this, a detailed understanding of the structure of the SAM-water interface generated from both formation and use of the SAM in an aqueous environment is elusive, and analytical measurements of the structure and chemistry of the SAM-water interface are an ongoing experimental challenge. To address this, we used neutron reflectometry (NR) to measure water association with both hydrophobic and hydrophilic SAMs under both wet and dry conditions. SAMs used for this study were made from hydrophobic decanethiol mixed with hydrophilic 11-azido-1-undecanethiol with compositions of 0-100% of the azide-terminated thiol. All SAMs were formed by conventional solution incubation of a Au substrate immersed in ethanol. Each SAM was characterized by grazing incidence angle reflection-absorption Fourier transfer infrared spectroscopy, contact angle goniometry, and electrochemical methods to confirm it was a completely formed monolayer with evidence of extensive crystalline-like domains. NR measured significant absorption of water into each SAM, ranging from 1.6 to 5.7 water molecules per alkyl thiol, when SAMs were immersed in water. Water infiltration was independent of SAM composition and terminal group hydrophilicity. These results demonstrate that water accesses defects, fluid regions, and heterogeneous domains inherent to even well-formed SAMs.
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Affiliation(s)
- Whitney A Fies
- Department of Chemistry and Texas Materials Institute , The University of Texas at Austin , 2506 Speedway STOP A5300 , Austin , Texas 78712 , United States
| | | | - Jeffrey E Dick
- Department of Chemistry , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Logan M Wilder
- Department of Chemistry and Texas Materials Institute , The University of Texas at Austin , 2506 Speedway STOP A5300 , Austin , Texas 78712 , United States
| | | | | | | | - Lauren J Webb
- Department of Chemistry and Texas Materials Institute , The University of Texas at Austin , 2506 Speedway STOP A5300 , Austin , Texas 78712 , United States
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Electric field induced proton transfer at α,ω-mercaptoalkanecarboxylic acids self-assembled monolayers of different chain length. J Electroanal Chem (Lausanne) 2018. [DOI: 10.1016/j.jelechem.2018.03.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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6
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Uebel M, Vimalanandan A, Laaboudi A, Evers S, Stratmann M, Diesing D, Rohwerder M. Fabrication of Robust Reference Tips and Reference Electrodes for Kelvin Probe Applications in Changing Atmospheres. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:10807-10817. [PMID: 28938076 DOI: 10.1021/acs.langmuir.7b02533] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The scanning Kelvin probe (SKP) is a versatile method for the measurement of the Volta potential difference between a sample and the SKP-tip (ΔψsampleSKP-tip). Based on suitable calibration, this technique is highly suited for the application in corrosion science due to its ability to serve as a very sensitive noncontact and nondestructive method for determining the electrode potential, even at buried interfaces beneath coatings or on surfaces covered by ultrathin electrolyte layers, which are not accessible by standard reference electrodes. However, the potential of the reference (i.e., the SKP-tip) will be influenced by variations of the surrounding atmosphere, resulting in errors of the electrode potential referred to the sample. The objective of this work is to provide a stable SKP-tip which can be used in different or changing atmosphere, e.g., within a wide range of relative humidity (approximately 0-99%-rh) or varying O2 partial pressure, without showing a change of its potential (note that the work functions measured in non-UHV atmospheres are electrochemical in nature [Hausbrand et al. J. Electrochem. Soc. 2008, 155 (7), C369-C379], and hence in the following we will refer to the potential of the SKP-tip instead of its work function). In that regard, the SKP-tip is in a first approach modified with self-assembled monolayers (SAMs) in order to create a hydrophobic barrier between the metallic surface and the surrounding atmosphere. The changes in potential upon varying relative humidity (ΔErh) of different bare metallic substrates are quantified, and it is shown that these potential differences cannot be minimized by SAMs. On the contrary, the ΔErh increases for every examined material system modified with SAMs. The major explanation for this observation is the dipole layer at the interface metal|SAM, causing an interfacial adsorption of water molecules even in a preferred orientation of their dipole moments, which leads to a changed work function and consequently to the correlated electrode potential. However, thin paraffin coatings were found to lead to a strongly reduced ΔErh, finally validated with novel robust Ag/Ag+ reference electrodes. It is also shown that nickel as SKP-tip material is seemingly more stable in varying atmospheric conditions compared to widely used Ni/Cr, stainless steel, or gold as SKP-tip material.
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Affiliation(s)
- M Uebel
- Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH , Max-Planck-Str. 1, 40237 Düsseldorf, Germany
| | - A Vimalanandan
- Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH , Max-Planck-Str. 1, 40237 Düsseldorf, Germany
| | - A Laaboudi
- Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH , Max-Planck-Str. 1, 40237 Düsseldorf, Germany
| | - S Evers
- Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH , Max-Planck-Str. 1, 40237 Düsseldorf, Germany
| | - M Stratmann
- Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH , Max-Planck-Str. 1, 40237 Düsseldorf, Germany
| | - D Diesing
- Faculty of Chemistry, University of Duisburg-Essen , Universitätsstr. 5, 45141 Essen, Germany
| | - M Rohwerder
- Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH , Max-Planck-Str. 1, 40237 Düsseldorf, Germany
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Steven JT, Golovko VB, Johannessen B, Marshall AT. Electrochemical stability of carbon-supported gold nanoparticles in acidic electrolyte during cyclic voltammetry. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2015.11.096] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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8
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Structural studies of self-assembled monolayers of 4-mercaptopyridine on gold electrodes with surface-enhanced Raman spectroscopy. J Solid State Electrochem 2015. [DOI: 10.1007/s10008-015-2869-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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9
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Safazadeh L, Berron BJ. Photopatterning of stable, low-density, self-assembled monolayers on gold. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:2689-2696. [PMID: 25689672 DOI: 10.1021/acs.langmuir.5b00001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Photoinitiated thiol-yne chemistry is utilized as a click reaction for grafting of acid-terminated alkynes to thiol-terminated monolayers on a gold substrate to create stable, low-density monolayers. The resulting monolayers are compared with a well-packed 11-mercaptoundecanoic acid monolayer and the analogous low-density monolayers prepared through a solution phase synthetic approach. The overall structuring of the monolayer prepared by solid-phase grafting is characterized by contact angle goniometry and Fourier transform infrared spectroscopy. The results show that the product monolayer has an intermediate surface energy and a more disordered chemical structuring compared to a traditional well-packed self-assembled monolayer, showing a low-packing density of the chains at the monolayer surface. The monolayer's structure and electrochemical stability were studied by reductive desorption of the thiolates. The prepared low-density monolayers have a higher electrochemical stability than traditional well-packed monolayers, which results from the crystalline structure at the gold interface. This technique allows for simple, fast preparation of low-density monolayers of higher stability than well-packed monolayers. The use of a photomask to restrict light access to the substrate yielded these low-density monolayers in patterned regions defined by light exposure. This general thiol-yne approach is adaptable to a variety of analogous low-density monolayers with diverse chemical functionalities.
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Affiliation(s)
- Leila Safazadeh
- Chemical and Materials Engineering, University of Kentucky , Lexington, Kentucky 40506-0046, United States
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Nováková Z, Oriňáková R, Fedorková AS, Oriňák A. Electrochemical study of self-assembled monolayer adsorption. J Solid State Electrochem 2014. [DOI: 10.1007/s10008-014-2455-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Stevens CA, Safazadeh L, Berron BJ. Thiol-yne adsorbates for stable, low-density, self-assembled monolayers on gold. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:1949-1956. [PMID: 24512439 DOI: 10.1021/la404940q] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We present a novel approach toward carboxylate-terminated, low-density monolayers on gold, which provides exceptional adsorbate stability and conformational freedom of interfacial functional groups. Adsorbates are synthesized through the thiol-yne addition of two thiol-containing head groups to an alkyne-containing tail group. The resulting monolayers have two distinct phases: a highly crystalline head phase adjacent to the gold substrate, and a reduced density tail phase, which is in contact with the environment. The ellipsometric thickness of 27 Å is consistent with the proposed structure, where a densely packed decanedithiol monolayer is capped with an 11 carbon long, second layer at 50% lateral chain density. The Fourier transform infrared peak at 1710 cm(-1) supports the presence of the carbonyl group. Further, the peaks associated with asymmetric and symmetric methylene stretching are shifted toward higher wavenumbers compared to those of well-packed self-assembled monolayers (SAMs), which shows a lower average crystallinity of the thiol-yne monolayers compared to a typical monolayer. Contact angle measurements indicate an intermediate surface energy for the thiol-yne monolayer surface, owing to the contribution of exposed methylene functionality at the surface in addition to the carbonyl terminal group. The conformational freedom at the surface was demonstrated through remodeling the thiol-yne surface under an applied potential. Changes in the receding contact angle in response to an external potential support the capacity for reorientation of the surface presenting groups. Despite the low packing at the solution interface, thiol-yne monolayers are resistant to water and ion transport (R(f) ~ 10(5)), supporting the presence of a densely structured layer at the gold surface. Further, the electrochemical stability of the thiol-yne adsorbates exceeded that of well-packed SAMs, requiring a more reductive potential to desorb the thiol-yne monolayers from the gold surface. The thiol-yne monolayer approach is not limited to carboxylate functionality and is readily adapted for low-density monolayers of varied functionality.
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Affiliation(s)
- Christopher A Stevens
- Chemical and Materials Engineering, University of Kentucky , Lexington, Kentucky 40506-0046, United States
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AOKI N, SATO K, HASEGAWA K, SANO S, KAGEYAMA M, UMEZAWA N, KONDO T. Self-Assembly Process of Flatly Adsorbed Porphyrin Self-Assembled Monolayer on a Au(111) Surface Studied by ex situ Scanning Tunneling Microscopy and Electrochemical Reductive Desorption Measurements. ELECTROCHEMISTRY 2014. [DOI: 10.5796/electrochemistry.82.385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Worley BC, Ricks WA, Prendergast MP, Gregory BW, Collins R, Cassimus JJ, Thompson RG. Anodic passivation of tin by alkanethiol self-assembled monolayers examined by cyclic voltammetry and coulometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:12969-12981. [PMID: 24063665 DOI: 10.1021/la402703w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The self-assembly of medium chain length alkanethiol monolayers on polycrystalline Sn electrodes has been investigated by cyclic voltammetry and coulometry. These studies have been performed in order to ascertain the conditions under which their oxidative deposition can be achieved directly on the oxide-free Sn surface, and the extent to which these electrochemically prepared self-assembled monolayers (SAMs) act as barriers to surface oxide growth. This work has shown that the potentials for their oxidative deposition are more cathodic (by 100-200 mV) than those for Sn surface oxidation and that the passivating abilities of these SAMs improve with increasing film thickness (or chain length). Oxidative desorption potentials for these films have been observed to shift more positively, and in a highly linear fashion, with increasing film thickness (~75 mV/CH2). Although reductive desorption potentials for the SAMs are in close proximity to those for reduction of the surface oxide (SnOx), little or no SnOx formation occurs unless the potential is made sufficiently anodic that the monolayers start to be removed oxidatively. Our coulometric data indicate that the charge involved with alkanethiol reductive desorption or oxidative deposition is consistent with the formation of a close-packed monolayer, given uncertainties attributable to surface roughness and heterogeneity phenomena. These experiments also reveal that the quantity of charge passed during oxidative desorption is significantly larger than what would be predicted for simple alkylsulfinate or alkylsulfonate formation, suggesting that oxidative removal involves a more complex oxidation mechanism. Analogous chronocoulometric experiments for short-chain alkanethiols on polycrystalline Au electrodes have evidenced similar oxidative charge densities. This implies that the mechanism for oxidative desorption on both surfaces may be very similar, despite the significant differences in the inherent dissolution characteristics of the two materials at the anodic potentials employed.
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Affiliation(s)
- Barrett C Worley
- Department of Chemistry & Biochemistry, Samford University , Birmingham, Alabama 35229-2236, United States
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Feng G, Niu T, You X, Wan Z, Kong Q, Bi S. Studies on the effect of electrode pretreatment on the coverage of self-assembled monolayers of dodecanethiol on gold by electrochemical reductive desorption determination. Analyst 2011; 136:5058-63. [DOI: 10.1039/c1an15642j] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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Haque AMJ, Kim K. Reusable bio-functionalized surfaces based on electrochemical desorption of benzenediazonium-grafted organic layers. Chem Commun (Camb) 2011; 47:6855-7. [DOI: 10.1039/c1cc11866h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Meunier-Prest R, Legay G, Raveau S, Chiffot N, Finot E. Potential-assisted deposition of mixed alkanethiol self-assembled monolayers. Electrochim Acta 2010. [DOI: 10.1016/j.electacta.2009.12.045] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Calvente JJ, López-Pérez G, Jurado JM, Andreu R, Molero M, Roldán E. Reorientation of thiols during 2D self-assembly: interplay between steric and energetic factors. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:2914-2923. [PMID: 19764782 DOI: 10.1021/la902981n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Reorientation of thiols during their 2D self-assembly is well established; however, little is known about its energetics and the factors that control its onset. We have developed a new strategy to determine the critical reorientational surface concentration (crsc) of thiols at the substrate/solution interface, which makes use of a cathodic stripping protocol. Its application to distinct homologous series of alkylthiols shows that the magnitude of the crsc and its variation with the molecular size is strongly dependent on the nature of the terminal group. Methyl-terminated alkylthiols reorient close to the saturation coverage of the lying-down phase, thus following their molecular size trend; whereas reorientation of alkylthiols bearing a negatively charged end group starts well below the monolayer coverage of the lying-down phase, with its onset being almost independent of the molecular size. Hydroxy-terminated alkylthiols show an intermediate behavior. A theoretical approach is developed to determine the reorientation equilibrium constant from the crsc value. The standard free energy of reorientation has been found to vary linearly with the alkyl chain length, and to increase upon replacing the terminal methyl group by a negatively charged one. A quantitative correlation between the reorientation equilibrium constant and the hydrophobicity of the molecule has been established. Overall, these findings have allowed us to disentangle the role of steric and energetic factors in the onset of the reorientation process of alkylthiols, demonstrating that their interplay can be finely tuned by varying either the alkyl chain length or the nature of the terminal group.
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Affiliation(s)
- Juan José Calvente
- Departamento de Química Física, Facultad de Química, Universidad de Sevilla, 41012, Sevilla, Spain.
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1,n-Alkanedithiol (n = 2, 4, 6, 8, 10) Self-Assembled Monolayers on Au(111): Electrochemical and Theoretical Approach. B KOREAN CHEM SOC 2009. [DOI: 10.5012/bkcs.2009.30.11.2549] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Uosaki K. Electrochemical oxidative formation of ordered monolayers of thiol molecules on Au(111) surface. CHEM REC 2009; 9:199-209. [DOI: 10.1002/tcr.200900002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Kondo T, Tamura K, Takakusagi S, Kitamura K, Takahasi M, Mizuki J, Uosaki K. Partial stripping of Ag atoms from silver bilayer on a Au(111) surface accompanied with the reductive desorption of hexanethiol SAM. J Solid State Electrochem 2009. [DOI: 10.1007/s10008-008-0764-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Dissolution kinetics of octadecanethiolate monolayers electro-adsorbed on Au(111). J Electroanal Chem (Lausanne) 2008. [DOI: 10.1016/j.jelechem.2008.01.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Han Y, Uosaki K. Effects of concentration and temperature on the formation process of decanethiol self-assembled monolayer on Au(111) followed by electrochemical reductive desorption. Electrochim Acta 2008. [DOI: 10.1016/j.electacta.2008.04.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Hara K, Akiyama R, Takakusagi S, Uosaki K, Yoshino T, Kagi H, Sawamura M. Self-Assembled Monolayers of Compact Phosphanes with Alkanethiolate Pendant Groups: Remarkable Reusability and Substrate Selectivity in Rh Catalysis. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200800884] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Hara K, Akiyama R, Takakusagi S, Uosaki K, Yoshino T, Kagi H, Sawamura M. Self-Assembled Monolayers of Compact Phosphanes with Alkanethiolate Pendant Groups: Remarkable Reusability and Substrate Selectivity in Rh Catalysis. Angew Chem Int Ed Engl 2008; 47:5627-30. [DOI: 10.1002/anie.200800884] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Catch and release cell sorting: electrochemical desorption of T-cells from antibody-modified microelectrodes. Colloids Surf B Biointerfaces 2008; 64:260-8. [PMID: 18394868 DOI: 10.1016/j.colsurfb.2008.02.010] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 02/03/2008] [Accepted: 02/04/2008] [Indexed: 11/23/2022]
Abstract
The development of integrated microsystems capable of interrogation, characterization and sorting of mammalian cells is highly significant for further advancement of point-of-care diagnostics and drug discovery fields. The present study sought to design a novel strategy for releasing antibody-bound cells through electrochemical disruption of the underlying antibody (Ab) layer. A microsystem for selective capture and release of cells consisted of an array of individually addressable gold microelectrodes fabricated on a glass substrate. Poly(ethylene glycol) (PEG) hydrogel photolithography was employed to make the glass regions non-fouling, thus, ensuring selective localization of proteins and cells on the microelectrodes. The gold surfaces were decorated with anti-CD4 Ab molecules using standard alkanethiol self-assembly and carbodiimide coupling approaches. The Ab-functionalized electrodes selectively captured model T-lymphocytes (Molt-3 cells) expressing CD4 antigen while minimal cell adhesion was observed on PEG hydrogel-modified glass substrates. Importantly, application of a reductive potential (-1.2V vs. Ag/AgCl reference electrode) resulted in release of surface-bound T-cells from the electrode surface. Cyclic voltammetry and fluorescence microscopy were employed to verify that the detachment of captured T-cells was indeed due to the electrochemical disruption of the underlying alkanethiol-Ab layer. In the future, the cell sorting approach described here may be combined with microfluidic delivery to enable Ab-mediated capture of T-lymphocytes or other cell types followed by release of select cells for downstream gene expression studies or re-cultivation.
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Possari R, Carvalhal RF, Mendes RK, Kubota LT. Electrochemical detection of cysteine in a flow system based on reductive desorption of thiols from gold. Anal Chim Acta 2006; 575:172-9. [PMID: 17723588 DOI: 10.1016/j.aca.2006.06.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2005] [Revised: 05/31/2006] [Accepted: 06/01/2006] [Indexed: 01/23/2023]
Abstract
A simple strategy for cysteine determination using flow-injection analysis with electrochemical detection is described. The approach is based on the chemisorptions reactions of the sulfur moiety of cysteine upon polycrystalline gold electrodes and its subsequent reductive desorption. The electrochemical measurements were accomplished by the application of differential pulse voltammetry (DPV) for the operational optimization and pulsed electrochemical detection (PED) in combination with flow-injection analysis for the electrochemical detection as time function. The electroactive species could be adsorbed in a potential level (0.1 V versus SCE), at other (-0.6 V versus SCE) occurs their reductive desorption from the electrode, while the analytical current is recorded simultaneously, and a third potential step is applied to the complete regeneration of the gold electrode surface (-1.3 V versus SCE). The linear response range was observed between 1.0 x 10(-6) and 6.0 x 10(-6) mol L(-1) with a good reproducibility (R.S.D.<3.2%) and sensitivity (1.1 microA/microM). The repeatability (a series of 27 continuous FIA peaks of 5. 0 micromol L(-1) of cysteine) was 3.8 % and the limit of detection was 5.0 x 10(-7) mol L(-1). The sample throughput was 23 samples per hour with a very high stability in its voltammetric response. The developed methodology was successfully used for the determination of cysteine in commercial supplementary food sample.
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Affiliation(s)
- Rodrigo Possari
- Instituto de Química, Universidade Estadual de Campinas-UNICAMP, CP 6154, CEP 13083-970, Campinas, SP, Brazil
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Immobilization of Hexacyanoferrate on a Gold Self-Assembled Monolayer, and its Application as a Sensor for Ascorbic Acid. Mikrochim Acta 2006. [DOI: 10.1007/s00604-006-0517-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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28
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Carvalhal R, Sanches Freire R, Kubota L. Polycrystalline Gold Electrodes: A Comparative Study of Pretreatment Procedures Used for Cleaning and Thiol Self-Assembly Monolayer Formation. ELECTROANAL 2005. [DOI: 10.1002/elan.200403224] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Wano H, Uosaki K. In Situ dynamic monitoring of electrochemical oxidative adsorption and reductive desorption processes of a self-assembled monolayer of hexanethiol on a Au(111) surface in KOH ethanol solution by scanning tunneling microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:4024-4033. [PMID: 15835970 DOI: 10.1021/la050209w] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Electrochemical oxidative formation and reductive desorption processes of a self-assembled monolayer (SAM) of hexanethiol on a Au(111) surface in KOH ethanol solutions containing various concentrations of hexanethiol were investigated by in situ scanning tunneling microscopy in real time. The generation and disappearance of vacancy islands (VIs), corresponding to the formation and desorption of the SAM, respectively, were observed as anodic and cathodic current, respectively, flowed when the thiol concentration was higher than ca. 1 microM. When the VIs disappeared after the reductive desorption of the SAMs, the herringbone structure corresponding to the (radical3 x 23) structure of Au(111), was observed on the surface, indicating that a clean reconstructed surface was exposed even in the hexanethiol ethanol solution. During both oxidative adsorption and reductive desorption of the SAMs, the shape of the steps of the gold substrate changed drastically and the step lines became parallel to the 121 direction of the Au(111) surface, suggesting that gold atoms on the surface were extremely mobile during these processes. The coalescence of adjacent vacancy islands and growth of larger islands triangular in shape accompanied with the disappearance of nearby smaller islands were observed, confirming that the VIs grew according to the Ostward ripening model.
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Affiliation(s)
- Hiromi Wano
- Physical Chemistry Laboratory, Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
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Chen RJ, Choi HC, Bangsaruntip S, Yenilmez E, Tang X, Wang Q, Chang YL, Dai H. An investigation of the mechanisms of electronic sensing of protein adsorption on carbon nanotube devices. J Am Chem Soc 2004; 126:1563-8. [PMID: 14759216 DOI: 10.1021/ja038702m] [Citation(s) in RCA: 245] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
It has been reported that protein adsorption on single-walled carbon nanotube field effect transistors (FETs) leads to appreciable changes in the electrical conductance of the devices, a phenomenon that can be exploited for label-free detection of biomolecules with a high potential for miniaturization. This work presents an elucidation of the electronic biosensing mechanisms with a newly developed microarray of nanotube "micromat" sensors. Chemical functionalization schemes are devised to block selected components of the devices from protein adsorption, self-assembled monolayers (SAMs) of methoxy(poly(ethylene glycol))thiol (mPEG-SH) on the metal electrodes (Au, Pd) and PEG-containing surfactants on the nanotubes. Extensive characterization reveals that electronic effects occurring at the metal-nanotube contacts due to protein adsorption constitute a more significant contribution to the electronic biosensing signal than adsorption solely along the exposed lengths of the nanotubes.
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Affiliation(s)
- Robert J Chen
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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Sumi T, Uosaki K. Electrochemical Oxidative Formation and Reductive Desorption of a Self-Assembled Monolayer of Decanethiol on a Au(111) Surface in KOH Ethanol Solution. J Phys Chem B 2004; 108:6422-8. [DOI: 10.1021/jp049558+] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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