Electrochemical and X-ray photoelectron spectroscopic evidence for differences in the binding sites of alkanethiolate monolayers chemisorbed at gold

Walczak, Mary M.; Alves, Carla A.; Lamp, Brian D.; Porter, Marc D.

doi:10.1016/0022-0728(95)04056-t

Cited by 257 publications

(237 citation statements)

References 71 publications

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“…This treatment produces a flat gold surface with predominant (111) orientation, as confirmed by STM. The average roughness factor of the substrates (1.2) was estimated by the iodine chemisorption method [28] and is in agreement with reported values for similar thin gold electrodes [29,30]. The mixed monolayers were prepared by substrate immersion in 1 : 1, 1 : 5, 1 : 10, and 1 : 20 11-Mercaptoundecanoic acid : 1-hexanethiol solutions in ethanol, in a total thiol concentration of 1 mM, for 24 h, and then removed, thoroughly rinsed with ethanol and pure water, and dried under a stream of nitrogen.…”

Section: Gold Surface Modificationsupporting

confidence: 73%

Immunosensor interface based on physical and chemical immunoglobulin G adsorption onto mixed self-assembled monolayers

Wang

Viana

Jin

et al. 2006

Bioelectrochemistry

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An immunosensor interface based on mixed hydrophobic self-assembled monolayers (SAMs) of methyl and carboxylic acid terminated thiols with covalently attached human Immunoglobulin G (hIgG), is investigated. The densely packed and organised SAMs were characterised by contact angle measurements and cyclic voltammetry. The effect of the non-ionic surfactant, Tween 20, in preventing nonspecific adsorption is addressed by ellipsometry during physical and covalent hIgG immobilization on pure and mixed SAMs, respectively. It is clearly demonstrated that nonspecific adsorption due to hydrophobic interactions of hIgG on methyl ended groups is totally inhibited, whereas electrostatic/hydrogen bonding interactions with the exposed carboxylic groups prevail in the presence of surfactant. Results of ellipsometry and Atomic Force Microscopy, reveal that the surface concentration of covalently immobilized hIgG is determined by the ratio of COOH / CH 3 -terminated thiols in SAM forming solution. Moreover, the ellipsometric data demonstrates that the ratio of bound anti-hIgG / hIgG depends on the density of hIgG on the surface and that the highest ratio is close to three. We also report the selectivity and high sensitivity achieved by chronoamperometry in the detection of adsorbed hIgG and the reaction with its antibody.

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Section: Gold Surface Modificationsupporting

confidence: 73%

Immunosensor interface based on physical and chemical immunoglobulin G adsorption onto mixed self-assembled monolayers

Wang

Viana

Jin

et al. 2006

Bioelectrochemistry

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“…Au -SR + e -=> Au + RS - (1) many electrochemical studies of the reaction (1) have been carried out because the peak area and the shape of the cathodic peak for the reductive desorption and its peak potential provide useful information of the SAM such as the adsorbed amount, stability, adsorption energy, orientation, and substrate morphology [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. For example, it was found that the longer the alkylchain, the more negative the reductive peak potential, reflecting the stronger van der Waals attractive interaction among alkylchains [17].…”

Section: Introductionmentioning

confidence: 99%

“…For example, it was found that the longer the alkylchain, the more negative the reductive peak potential, reflecting the stronger van der Waals attractive interaction among alkylchains [17]. The reductive desorption process has been investigated by many techniques including electrochemistry [17][18][19][20][21][22][23][24][25][26], FT-IR [27][28][29], electrochemical QCM [30][31][32], and in situ STM [33][34][35][36]. Several groups suggested the formation of an "aggregate" or "micelle" near or on the electrode surface after the reductive desorption of the SAM [28,33,35].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical oxidative adsorption and reductive desorption of a self-assembled monolayer of decanethiol on the Au(111) surface in KOH+ethanol solution

Sumi

Wano

Uosaki

2003

Journal of Electroanalytical Chemistry

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The electrochemical characteristics of an Au(111) electrode were investigated in 0.1 M KOH ethanol solutions containing various concentrations of decanethiol. Anodic and cathodic peaks corresponding to the oxidative adsorption and reductive desorption, respectively, of a self-assembled monolayer (SAM) of decanethiol were observed. Both peaks negatively shifted with the increase in the thiol concentration by ca. 57 mV/decade, showing that the redox process is a one-electron process. The adsorbed amount determined from the charge corresponding to the reductive desorption increased with an increase in the decanethiol concentration but never reached the saturated amount as long as the cyclic voltammograms were continuously recorded with the sweep rate of 10 -200 mV s-1. It increased with the holding time at +0.1 V, which was much more positive than the anodic peak potential, and reached the saturated amount in ca. 10 min in the 10 μM thiol solution. The reductive peak potential also negatively shifted with the holding time but for a longer period. It kept shifting for ca. 60 min in the 10 μM thiol solution, which is much longer than the time when the adsorbed amount reached the saturated value. These results suggest that the formation of a highly ordered SAM requires a much longer time than the adsorption of the thiol.2

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“…By comparing the peak positions in the voltammograms to similar systems reported on previously, we assigned the peak at approximately -0.90 V to desorption of alkanethiols from the terraces [39], and the peaks at -1.08 to -1.37 V to the desorption of alkanethiols adsorbed on the steps of polycrystalline Au [40][41].…”

Section: Characterization Of the Sensor Surfacesmentioning

confidence: 68%

Effect of alkanethiol molecular structure on sensitivity of surface plasmon resonance sensor

Suherman

Morita

Kawaguchi

2015

Sensors and Actuators B: Chemical

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This work aims to find the key factor determining the detection limit for an indirect competitive inhibition immunoassay using surface plasmon resonance (SPR) sensing. In our previous work, the thiol solution concentration used in a self-assembly process highly affected the alkanethiol monolayer structure on the sensor surface [Suherman et al., 2014]. It was noticed that the monolayer structure determined the immunoassay sensitivity due to the orientation and the surface concentration of antigen in domain structure of monolayer. To study the effect of orientation of antigen, we examined here three types of alkanethiol compounds: dithiobis(succinimidyl undecanoate) (DSU; straight-chain alkanethiol), carboxy-EG 6 -undecanethiol (CEG 6 ; flexible-chain alkanethiol), and(C 2 -NTA; three-branched alkanethiol). By electrochemical reductive desorption, the surface concentration of DSU, CEG 6 , and C 2 -NTA were estimated to be 6.6 × 10 -10 , 8.5 × 10 -10 , 4.6 × 10 -10 mol cm -2 , respectively. Subsequently, SPR suggested that the ratios of immobilized antigen (clenbuterol) per thiol were 0.13, 0.16, and 0.15 for DSU, CEG 6 , and C 2 -NTA, respectively. This suggests that the amount of immobilized clenbuterol was defined by the molecular size of clenbuterol. Sensor surface structures on a molecular scale were evaluated using high-resolution scanning tunneling microscopy (STM), which showed tilted clenbuterol with θ DSU > θ CEG6 > θ C2-NTA . For SPR sensing of clenbuterol, C 2 -NTA showed the highest sensitivity (LOD = 10 ppt) among the examined alkanethiols, because clenbuterol formed a laid-on structure. Based on kinetics, the key factor for sensing performance is discussed.2

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Electrochemical and X-ray photoelectron spectroscopic evidence for differences in the binding sites of alkanethiolate monolayers chemisorbed at gold

Cited by 257 publications

References 71 publications

Immunosensor interface based on physical and chemical immunoglobulin G adsorption onto mixed self-assembled monolayers

Immunosensor interface based on physical and chemical immunoglobulin G adsorption onto mixed self-assembled monolayers

Electrochemical oxidative adsorption and reductive desorption of a self-assembled monolayer of decanethiol on the Au(111) surface in KOH+ethanol solution

Effect of alkanethiol molecular structure on sensitivity of surface plasmon resonance sensor

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