Effect of Ormosil and Polymer Doping on the Morphology of Separately and Co-hydrolyzed Silica Films Formed by a Two-Step Aqueous Processing Method

Goring, Gillian L. G.; Brennan, John D.

doi:10.1021/cm071577j

Cited by 12 publications

(19 citation statements)

References 79 publications

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“…We were unable to examine all of the hydrophobic glasses above 15% modification due to a phase separation phenomenon that leads to a loss of optical transparency. Phase separation can be minimized by co-hydrolysis of the organosilane reagents, as employed here, instead of separate hydrolyses followed by mixing [8,45,46]. Our glasses appear to be under the reported threshold for phase separation of co-hydrolyzed samples; for example, glasses with up to 20% by volume of methyltriethoxysilane or 5% propyltrimethoxysilane have been prepared in tetraethoxysilane (TEOS) with no sign of phase separation, as monitored by several optical techniques [8,46].…”

Section: Discussionmentioning

confidence: 95%

“…Phase separation can be minimized by co-hydrolysis of the organosilane reagents, as employed here, instead of separate hydrolyses followed by mixing [8,45,46]. Our glasses appear to be under the reported threshold for phase separation of co-hydrolyzed samples; for example, glasses with up to 20% by volume of methyltriethoxysilane or 5% propyltrimethoxysilane have been prepared in tetraethoxysilane (TEOS) with no sign of phase separation, as monitored by several optical techniques [8,46]. The higher threshold for propyltrimethoxysilane in the current work (15% molar) may be due to slight differences in preparation (TMOS versus TEOS) and in the commercial source of reagents.…”

Section: Discussionmentioning

confidence: 99%

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Favourable influence of hydrophobic surfaces on protein structure in porous organically-modified silica glasses

et al. 2008

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Organically-modified siloxanes were used as host materials to examine the influence of surface chemistry on protein conformation in a crowded environment. The sol-gel materials were prepared from tetramethoxysilane and a series of monosubstituted alkoxysilanes, RSi(OR′) 3 , featuring alkyl groups of increasing chain length in the R-position. Using circular dichroism spectroscopy in the far-UV region, apomyoglobin was found to transit from an unfolded state to a native-like helical state as the content of the hydrophobic precursor increased from 0-15%. At a fixed molar content of 5% RSi(OR') 3 , the helical structure of apomyoglobin increased with the chain length of the R-group, i.e. methyl < ethyl < n-propyl < n-butyl < n-hexyl. This trend also was observed for the tertiary structure of ribonuclease A, suggesting that protein folding and biological activity are sensitive to the hydrophilic/hydrophobic balance of neighboring surfaces. The observed changes in protein structure did not correlate with total surface area or the average pore size of the modified glasses, but scanning electron microscopy images revealed an interesting relationship between surface morphology and alkyl chain length. The unexpected benefit of incorporating a low content of hydrophobic groups into a hydrophilic surface may lead to materials with improved biocompatibility for use in biosensors and implanted devices.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Favourable influence of hydrophobic surfaces on protein structure in porous organically-modified silica glasses

et al. 2008

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“…Differences in phase translate into differences in hardness and cross-linking of the sol-gel-derived films. 63 The films did not show any features when imaged with SEM, which demonstrates a homogeneous material at the micrometre scale. Heterogeneity occurred at a very fine level as shown by AFM images and nanofeatures were observed at lower Z-ranges (0-10 nm for height or 0-5 for phase images).…”

Section: Characterisation Of the Optimum Ph Sensor Materialsmentioning

confidence: 91%

The development and characterisation of novel hybrid sol–gel-derived films for optical pH sensing

et al. 2012

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This paper focuses on the development and detailed characterisation of a novel hybrid sol-gel material derived from 3-glycidoxypropyltrimethoxysilane (GPTMS) and ethyltriethoxysilane (ETEOS). The material has been doped with a fluorescent pH-sensitive dye, modified 8-hydroxy-1,3,6-pyrene trisulfonic acid (HPTS) and its application as a high-performance optical ratiometric pH sensor has been demonstrated. The optimum sol-gel-based material composition has been characterised using atomic force microscopy (AFM), scanning electron microscopy in combination with energy dispersive X-ray spectroscopy (SEM-EDX), thermal gravimetric-infrared (TGA-IR) analysis, Fourier transform infrared (FT-IR) and Raman spectroscopy, solid state 29 Si and 13 C nuclear magnetic resonance (NMR). AFM and SEM images demonstrated a high degree of homogeneity of the pH films. FT-IR, Raman and NMR results have shown that hydrolysis and condensation reactions were almost completed and extensive crosslinking occurred in the final material. They also revealed that an opening of the epoxy ring in GPTMS took place which was key to optimum pH response. The pH sensor produced using the hybrid material compares very well with the current state-of-the-art and exhibits very good reversibility, reproducibility, stability, short response time and no leaching. The dynamic range extends from pH 5.0 to 8.0 which is compatible with bioprocessing, environmental and clinical monitoring applications.

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“…Although AFM has been widely used to observe and explore phase-separation phenomena in nongradient organosilane and organothiol monolayers, in thicker sol–gel-derived organosilane films, , and along thiol and polymer , gradients, it has not yet been broadly applied in studies of phase separation along organosilane-based chemical gradients. AFM has, however, been used to characterize the density of gold nanoparticles adsorbed on amine-terminated organosilane gradients and to determine the surface potential on pH-tunable gradients .…”

Section: Gradient Propertiesmentioning

confidence: 99%

Organosilane Chemical Gradients: Progress, Properties, and Promise

Collinson

Higgins²

2017

Langmuir

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Chemical gradients play an important role in nature, driving many different phenomena critical to life, including the transport of chemical species across membranes and the transport, attachment, and assembly of cells. Taking a cue from these natural processes, scientists and engineers are now working to develop synthetic chemical gradients for use in a broad range of applications, such as in high-throughput investigations of surface properties, as means to guide the motions and/or assembly of liquid droplets, vesicles, nanoparticles, and cells and as new media for stationary-phase-gradient chemical separations. Our groups have been working to develop new methods for preparing chemical gradients from organoalkoxysilane and organochlorosilane precursors and to obtain a better understanding of their properties on macroscopic to microscopic length scales. This review highlights our recent work on the development of controlled-rate infusion and infusion-withdrawal dip-coating methods for the preparation of gradients on planar glass and silicon substrates, on thin-layer chromatography plates, and in capillaries and monoliths for liquid chromatography. We also cover the new knowledge gained from the characterization of our gradients using sessile drop and Wilhelmy plate dynamic water contact angle measurements, X-ray photoelectron spectroscopy mapping, and single-molecule tracking and spectroscopy. Our studies reveal important evidence of phase separation and cooperative interactions occurring along multicomponent gradients. Emerging concepts and new directions in the preparation and characterization of organosilane-based chemical gradients are also discussed.

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Effect of Ormosil and Polymer Doping on the Morphology of Separately and Co-hydrolyzed Silica Films Formed by a Two-Step Aqueous Processing Method

Cited by 12 publications

References 79 publications

Favourable influence of hydrophobic surfaces on protein structure in porous organically-modified silica glasses

Favourable influence of hydrophobic surfaces on protein structure in porous organically-modified silica glasses

The development and characterisation of novel hybrid sol–gel-derived films for optical pH sensing

Organosilane Chemical Gradients: Progress, Properties, and Promise

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