Hydrolysis and Condensation of Self-Assembled Monolayers of (3-Mercaptopropyl)trimethoxysilane on Ag and Au Surfaces

Thompson, Wade R.; Cai, Mei; Ho, Mankit; Pemberton, Jeanne E.

doi:10.1021/la960795g

Cited by 114 publications

(112 citation statements)

References 65 publications

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“…Consistent with the ability of various thiol compounds to form self-assembled monolayers on gold electrodes [43], the chemisorption of MPTMS on gold has been pointed out by several techniques, including X-ray photoelectron spectroscopy [24], infra-red and Raman spectrometries [24], cyclic voltammetry [23,25,27], scanning tunneling microscopy [44], and electrochemical impedance spectroscopy [28]. This was often the starting point to build silica-based thin (or thick) films on the gold surface [24 -26, 28, 34], with improved adhesion in comparison to silica films not formed on the basis of MPTMS [34,45].…”

Section: Self-assembly Of Mptms Versus Condensationmentioning

confidence: 70%

Electrochemically‐Induced Deposition of Amine‐Functionalized Silica Films on Gold Electrodes and Application to Cu(II) Detection in (Hydro)Alcoholic Medium

Walcarius

Sibottier

2005

Electroanalysis

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Well-adherent amine-functionalized porous silica films have been deposited on gold electrodes by combining the selfassembly technology, the sol -gel process, and the electrochemical modulation of pH at the electrode/solution interface. A partial self-assembled monolayer of mercaptopropyl-trimethoxysilane (MPTMS) was first formed on disposable gold electrodes from recordable CDs (Au-CDtrodes). The so pretreated MPTMS-Au-CDtrodes were immersed in a stable sol solution (pH 3) containing (3-aminopropyl)-triethoxysilane (APTES) and tetraethoxysilane (TEOS). Polycondensation of the APTES and TEOS precursors was then achieved by applying a negative potential for a given period of time to generate a local pH increase at the electrode/solution interface and promote the deposition of the amine functionalized silica film adhering well to the electrode surface owing to the MPTMS monolayer acting somewhat as a "molecular glue". Various parameters affecting the electrodeposition process have been studied and the film permeability to redox probes in solution was characterized by cyclic voltammetry. The amine-functionalized silica film electrodes were then applied to the preconcentration of copper(II) species prior to their electrochemical detection by anodic stripping differential pulse voltammetry. Getting high sensitivity has however required the application of an electrochemical pre-activation step as the majority of the organo-functional groups were in the form of ammonium moieties (because the film was prepared from an acidic sol). This was achieved by applying a sufficiently negative potential to the electrode surface to reduce protons and increase consequently the amine-to-ammonium ratio within the film and, thus, the efficiency of the precocentration process. The resulting device was then optimized for copper(II) determination in hydroalcoholic medium, giving rise to a linear response in the 0.1 -10 mM concentration range.

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Section: Self-assembly Of Mptms Versus Condensationmentioning

confidence: 70%

Electrochemically‐Induced Deposition of Amine‐Functionalized Silica Films on Gold Electrodes and Application to Cu(II) Detection in (Hydro)Alcoholic Medium

Walcarius

Sibottier

2005

Electroanalysis

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“…Other bands between 1200 and 500 cm À1 are associated with Si À O À Si or Si À OH band vibration of the siliceous framework, e.g., 1080 cm À1 band with the Si À O À Si asymmetric bond stretching vibration and 960 cm À1 band with the Si À OH bond stretching vibration. The methoxy groups of MPTMS are indicated spectrally by a significant decrease in the intensity of the 960 cm À1 band [39]. The band in 580 cm…”

Section: Characterizing the Organofunctionalization Of Sol-mentioning

confidence: 99%

Thiol‐Functionalized Silica Thin Film Modified Electrode in Determination of Mercury Ions in Natural Water

Cesarino

Cavalheiro

2008

Electroanalysis

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The use of a thin thiol-functionalized silica film modified glassy carbon electrode in the determination of Hg(II) ions in a natural water sample is described. A typical measurement involves two successive steps: a glassy carbon electrode coated with a thin mesoporous silica film containing 10% of mercaptopropyl groups, according to the MPTMS/TEOS ratio in the starting sol-gel, was first immersed into the accumulation medium for 15 min, then removed, and finally transferred into a detection solution containing KCl 1.0 mol L À1 where detection was performed by anodic stripping voltammetry. In this medium the previously accumulated Hg 2þ species complexed by the thiol groups in an open circuit preconcentration step is then directly reduced at À 0.6 V during 60 s prior to be quantified by a differential pulse anodic scan from À 0.6 to 0.3 V (vs. Ag/AgCl). A stripping peak appeared at about À 0.01 V, which is directly proportional to the quantity of the analyte previously accumulated into the film. The best results were obtained under the following conditions: 100 mV pulse amplitude and 10 mV s À1 scan rate in 1.0 mol L À1 KCl solution pH 2.0. Using such parameters a linear dynamic range from 1.00 to 10.0 Â 10 À8 mol L À1 Hg(II) was observed with a limit of detection of 4.3 nmol L À1 for an accumulation time of 15 min. Hg(II) spiked in a natural water sample was determined between 97.0 and 101.4% mean recovery at 10 À8 mol L À1 level. The results indicate that this electrode is sensitive and selective for the Hg(II)determination.

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“…The coupling agent must contain at least two functionalities, one interacting with the support, the other with the protein to be deposited. The deposition process of the organic material can be achieved by chemical adsorption from solution (Thompson et al, 1997) or by reaction with hydroxyl groups present on the substrate (Kallury et al, 1994). Proteins could be anchored to the immobilized organic material by chemical reaction with the reactive groups of the coupling agents.…”

Section: Introductionmentioning

confidence: 99%

Preparation, morphological characterization, and activity of thin films of horseradish peroxidase

Vianello

Zennaro

Paolo

et al. 2000

Biotechnol. Bioeng.

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Active uniform films of horseradish peroxidase (HRP) have been prepared by covalent binding on Si/SiO2 or glass supports previously activated by silanization and succinylation. Labeling by fluorescent or by Electron Spin Resonance (ESR) probes was used to quantify the surface density of active groups and of horseradish peroxidase. Atomic Force Microscopy (AFM) imaging was used to characterize the surface morphology. We observed that a non‐uniform protein adsorption due to physical interactions was present when the supports were not activated for covalent binding and was, in large part, removed by washing. The enzyme deposited by covalent binding formed homogeneous layers with a height in the range 60–90 Å. By using a fluorescent label, we calculated a protein density of 3.6 × 1012 molecules cm−2 on Si/SiO2, corresponding to an estimated area per molecule of 2800 Å2 which is in agreement with the value expected on the basis of the crystallographic data considering the formation of a monomolecular layer. The protein density of the layer immobilized on glass was similar (1.9 ×1012 molecules cm−2). The enzyme immobilized on both supports showed a kcat/KM being of the order of 3–5×105 M−1s−1 that is 1/20th of free HRP. The half‐life time of the activity of the enzyme immobilized by covalent binding was longer than 40 days at 6°C. © 2000 John Wiley & Sons, Inc. Biotechnol Bioeng 68: 488–495, 2000.

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Hydrolysis and Condensation of Self-Assembled Monolayers of (3-Mercaptopropyl)trimethoxysilane on Ag and Au Surfaces

Cited by 114 publications

References 65 publications

Electrochemically‐Induced Deposition of Amine‐Functionalized Silica Films on Gold Electrodes and Application to Cu(II) Detection in (Hydro)Alcoholic Medium

Electrochemically‐Induced Deposition of Amine‐Functionalized Silica Films on Gold Electrodes and Application to Cu(II) Detection in (Hydro)Alcoholic Medium

Thiol‐Functionalized Silica Thin Film Modified Electrode in Determination of Mercury Ions in Natural Water

Preparation, morphological characterization, and activity of thin films of horseradish peroxidase

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