In Situ Quartz Crystal Microgravimetric Studies of Molecular Adsorbates Containing Thiol and Hydroquinone Moieties Bound to Au(111) Surfaces in Aqueous Electrolytes

Mo, Yibo; Sandifer, Marnita; Sukenik, Chaim N.; Barriga, Raul J.; Soriaga, Manuel P.; Scherson, Daniel Alberto

doi:10.1021/la00012a007

Cited by 21 publications

(15 citation statements)

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“…Thus, assuming that the contribution to changes in the frequency from diffusional species is negligible, and also that only protons move across the interface between the film and the solution upon the redox reaction, the number of water molecules (solvation) accompanying each proton was calculated, from the surface coverage of the Os complex (4.0 × 10 -10 mol cm -2 ) and the frequency change (6.1 Hz), to be 7.5. Similar results have been previously reported by Scherson et al, who found (also using an ECQM) that, for thiol-substituted quinones adsorbed on gold, the redox reaction gave rise to a change in solvation of about 3 water molecules …”

Section: Resultssupporting

confidence: 91%

Dithiobissuccinimidyl Propionate as an Anchor for Assembling Peroxidases at Electrodes Surfaces and Its Application in a H₂O₂ Biosensor

et al. 1999

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Exposure of gold surfaces to solutions of dithiobis N-succinimidyl propionate (DTSP) gives rise to the modification of the surface with N-succinimidyl-3-thiopropionate (NSTP) which can, in turn, react with amino groups allowing for the covalent immobilization of enzymes such as horseradish peroxidase (HRP). The coverage of NSTP has been estimated to be of the order of 1.3 x 10(-10) from the charge consumed during its reductive desorption. The binding reaction of HRP with NSTP modified gold surfaces has been studied with the quartz crystal microbalance, and the results suggest that the immobilization process involves two steps in which the first (faster) appears to correspond to the rapid incorporation of the enzyme whereas the second is likely due to the slow incorporation of additional enzyme and/or reorganization of the immobilized layer. Spectrophotometric and electrochemical assays indicate that the immobilized HRP retains its enzymatic activity after immobilization onto the DTSP modified gold surface. The amount of immobilized (and active) HRP was estimated from QCM and spectrophotometric measurements to be of the order of 1.5 x 10(-11) mol/cm2. A peroxide biosensor was developed making use of a gold surface modified with DTSP and HRP employing Os and Ru complexes of 1,10-phenanthroline 5,6-dione (phen-dione) of the type [M(phendione)x(L)3-x]+2 (where L = 1,10-phenanthroline or 2,2'-bipyridine, x = 1-3) as mediators with the quinone moieties being the active component. The efficiency of the mediators increased with increasing number of phendione ligands.

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Section: Resultssupporting

confidence: 91%

Dithiobissuccinimidyl Propionate as an Anchor for Assembling Peroxidases at Electrodes Surfaces and Its Application in a H₂O₂ Biosensor

et al. 1999

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“…The slope of k 1 0X07542, k 2 0X1793 corresponded to M I i 8X0 gamol and M II i 19X0 gamol by ®tting each segment, respectively. The values here were larger than the results of Mo et al [28] (2,5-dihydroxythiophenol (DHTP), 2,5-dihydroxybenzyl mercaptan (DHBM), and 2,5-dihydroxy-4-methylbenzyl mercaptan (DHMBM), respectively). We supposed the process was: ®rst, 4PHQ was adsorbed on the Pt electrode surface.…”

Section: Resultscontrasting

confidence: 88%

“…The experimental results were smaller than the calculated value, which may have been caused by the disturbing of the potential to opposite charge ions. Compared with the results obtained by Mo et al [28], the surface coverage was much higher than their results (0.27, 0.30 and 0.15 nmolacm 2 for 2,5-dihydroxythiophenol, 2,5-dihydroxybenzyl mercaptan, and 2,5-dihydroxy-4-methylbenzyl mercaptan, respectively), which is in accordance with the change of masses above. We suppose that the reason for this difference is the difference in the substitution.…”

Section: Resultssupporting

confidence: 87%

EQCM Characterization of Self-Assembled Kinetics of 4-Pyridyl Hydroquinone at Pt Surface and Its Ion Transfer in Electrochemical Redox

et al. 1999

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The adsorbed kinetics, proton transportation in electrochemical redox process of 4-pyridyl hydroquinone (4PHQ) self-assembled monolayer (SAM) modi®ed Pt electrode were studied by electrochemical quartz crystal microbalance (EQCM) in situ. It proved that the electrode was modi®ed by a monolayer and underwent a rapid electron transfer. It was a slow adsorbed kinetic process. The ion transfer in the electrochemical redox at the SAM-modi®ed electrode surface mainly involved into the hydrate hydrogen ion.

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“…The aligned orientation of alkanethiol molecules is one of the most attractive features of the self-assembled monolayers (SAMs) of such molecules. The monolayers of various types of alkanethiol derivatives with covalently tethered electroactive groups have been investigated in detail. − In such SAMs, it is expected that the orientation of the electroactive moiety, lateral interaction among the active centers, and microenvironment for them are highly regulated. The structure of the SAM may be governed by a number of factors including alkyl chain length, counterion involved in the redox reaction, and surface density of the thiol.…”

Section: Introductionmentioning

confidence: 99%

Voltammetric and Electroreflectance Study of Thiol-Functionalized Viologen Monolayers on Polycrystalline Gold: Effect of Anion Binding to a Viologen Moiety

et al. 1999

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The monolayers of thiol-functionalized viologens, i.e., dihexafluorophosphate salts of N-butyl-N‘-(4-mercaptobutyl)-4,4‘-bipyridinium (C4V2+C4SH) and N-pentyl-N‘-(5-mercaptopentyl)-4,4‘-bipyridinium (C5V2+C5SH), on a polycrystalline gold electrode were characterized in several aqueous electrolyte solutions using cyclic voltammetry and electroreflectance (ER) spectroscopy. The voltammetric response for the viologen dication/radical cation couple (V2+/V•+) in Na2SO4, K2SO4, KPF6, or KF solution was found to be electrolyte anion dependent. However, considerable differences due to the electrolyte anion or the alkyl chain length in the fractional content of dimer forms in the V•+ state and the average orientation of the V•+ moiety, both estimated from the results of ER spectral measurements, were not observed. A large voltammteric peak width was observed in KF solution. Because the voltammetric measurements suggested a strong and weak binding to the viologen moiety respectively for PF6 - and F- ions, the dependence of voltammetric response on the concentration of PF6 - was investigated quantitatively for a monolayer of C4V2+C4SH in the mixed solutions of KPF6 and KF at a constant ionic strength. It was found that one PF6 - ion additionally binds to a viologen moiety upon the oxidation of V•+ to V2+. The ratio of the binding constant to V2+ and V•+ was estimated to be approximately 1.2 × 104 M-1 at an ionic strength of electrolyte of 0.4 M. The absence of considerable dependence of the PF6 - binding on the ionic strength was suggested by voltammetric measurements in the solutions containing solely KPF6. The electron-transfer rate constants for the monolayers were estimated to be no less in the order of magnitude than 1 × 104 s-1.

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In Situ Quartz Crystal Microgravimetric Studies of Molecular Adsorbates Containing Thiol and Hydroquinone Moieties Bound to Au(111) Surfaces in Aqueous Electrolytes

Cited by 21 publications

References 0 publications

Dithiobissuccinimidyl Propionate as an Anchor for Assembling Peroxidases at Electrodes Surfaces and Its Application in a H₂O₂ Biosensor

Dithiobissuccinimidyl Propionate as an Anchor for Assembling Peroxidases at Electrodes Surfaces and Its Application in a H₂O₂ Biosensor

EQCM Characterization of Self-Assembled Kinetics of 4-Pyridyl Hydroquinone at Pt Surface and Its Ion Transfer in Electrochemical Redox

Voltammetric and Electroreflectance Study of Thiol-Functionalized Viologen Monolayers on Polycrystalline Gold: Effect of Anion Binding to a Viologen Moiety

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In Situ Quartz Crystal Microgravimetric Studies of Molecular Adsorbates Containing Thiol and Hydroquinone Moieties Bound to Au(111) Surfaces in Aqueous Electrolytes

Cited by 21 publications

References 0 publications

Dithiobissuccinimidyl Propionate as an Anchor for Assembling Peroxidases at Electrodes Surfaces and Its Application in a H2O2 Biosensor

Dithiobissuccinimidyl Propionate as an Anchor for Assembling Peroxidases at Electrodes Surfaces and Its Application in a H2O2 Biosensor

EQCM Characterization of Self-Assembled Kinetics of 4-Pyridyl Hydroquinone at Pt Surface and Its Ion Transfer in Electrochemical Redox

Voltammetric and Electroreflectance Study of Thiol-Functionalized Viologen Monolayers on Polycrystalline Gold: Effect of Anion Binding to a Viologen Moiety

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Dithiobissuccinimidyl Propionate as an Anchor for Assembling Peroxidases at Electrodes Surfaces and Its Application in a H₂O₂ Biosensor

Dithiobissuccinimidyl Propionate as an Anchor for Assembling Peroxidases at Electrodes Surfaces and Its Application in a H₂O₂ Biosensor