Search results for "Silanes"
showing 10 items of 51 documents
Performance of different C18 columns in reversed-phase liquid chromatography with hydro-organic and micellar-organic mobile phases
2014
Column selection in reversed-phase liquid chromatography (RPLC) can become a challenge if the target compounds interact with the silica-based packing. One of such interactions is the attraction of cationic solutes to the free silanols in silica-based columns, which is a slow sorption-desorption interaction process that gives rise to tailed and broad peaks. The effect of silanols is minimised by the addition of a competing agent in the mobile phase, such as the anionic surfactant sodium dodecyl sulphate (SDS). In micellar-organic RPLC, the adsorption of an approximately fixed amount of SDS monomers gives rise to a stable modified stationary phase, with properties remarkably different from th…
Performance of amines as silanol suppressors in reversed-phase liquid chromatography
2016
In reversed-phase liquid chromatography, cationic basic compounds yield broad and asymmetrical peaks, as a result of their ionic interaction with the anionic free silanol groups present in the silica-based stationary phases (commonly derivatised with C18 groups). A simple way to improve the peak shape is the addition to the hydro-organic mobile phase of a reagent (usually called additive) with cationic character. This associates with the stationary phase to prevent the access of analytes to the free silanol groups. Cationic additives may interact electrostatically with the anionic silanols. The hydrophobic region of the additive may also associate with the alkyl chains bound to the stationa…
3D-printing-assisted fabrication of chitosan scaffolds from different sources and cross-linkers for dental tissue engineering
2021
The aim of the present study was to fabricate and characterise chitosan scaffolds from animal and fungal sources, with or without gelatine as a co-polymer, and cross-linked to 3-glycidyloxyproply trimethoxysilane (GPTMS) or genipin for application in dental root tissue engineering. Chitosan-based scaffolds were prepared by the emulsion freeze-drying technique. Scanning electron microscopy (SEM) and nano-focus computed tomography (nano-CT) were used to characterise scaffold microstructure. Chemical composition and cross-linking were evaluated by Fourier transform infrared-attenuated total reflectance spectroscopy. Compression tests were performed to evaluate scaffold mechanical properties. S…
New insights in the formation of silanol defects in silicalite-1 by water intrusion under high pressure.
2010
International audience; The "water-silicalite-1" system is known to act as a molecular spring. The successive intrusion-extrusion cycles of liquid water in small crystallites (6 × 3 × 0.5 μm(3)) of hydrophobic silicalite-1 were studied by volumetric and calorimetric techniques. The experiments displayed a decrease of the intrusion pressure between the first intrusion-extrusion cycle and the consecutive ones, whereas the extrusion pressures remained unchanged. However, neither XRD studies nor SEM observations revealed any structural and morphological modifications of silicalite-1 at the long-range order. Such a shift in the value of the intrusion pressure after the first water intrusion-extr…
A solid device based on doped hybrid composites for controlling the dosage of the biocide N-(3-aminopropyl)-N-dodecyl-1,3-propanediamine in industria…
2015
A colorimetric composite device is proposed to determine the widely used biocide N-(3-aminopropyl)-N-dodecyl-1,3-propanediamine (ADP).This sensing device is based on a film of 1,2-Naphthoquinone-4-sulfonate (NQS) embedded into polydimethylsiloxane-tetraethylortosilicate-SiO2 nanoparticles composite (PDMS-TEOS-SiO2NPs). Semiquantitative analysis can be performed by visual inspection. Digitalized image or diffuse reflectance (DR) measurements can be carried out for quantitative analysis. Satisfactory detection limit (0.018%, w/v) and relative standard deviations <12% were achieved. The proposed device has been applied for the determination of ADP in detergent industrial formulations with reco…
Mineralization of SaOS-2 cells on enzymatically (silicatein) modified bioactive osteoblast-stimulating surfaces.
2005
There is a demand for novel bioactive supports in surgery, orthopedics, and tissue engineering. The availability of recombinant silica-synthesizing enzyme (silicatein) opens new possibilities for the synthesis of silica-containing bioactive surfaces under ambient conditions that do not damage biomolecules like proteins. Here it is shown that growth of human osteosarcoma SaOS-2 cells on cluster plates precoated with Type 1 collagen is not affected by additional coating of the plates with the recombinant silicatein and incubation with its enzymatic substrate, tetraethoxysilane (TEOS). However, the enzymatic modification of the plates by biosilica deposition on the protein-coated surface cause…
Hydrolytically stable chemically bonded silica supports with metal complexating ligands: Synthesis, characterization and use in high-performance liga…
1982
A silica of 14 nm pore size was reacted according to two procedures with the following silanes: γ-aminopropyltriethoxysilane (1), N-aminoethyl-N′-aminopropyltrimethoxysilane (2), N-aminoethyl-N′-aminoethyl-N″-aminopropyltrimethoxysilane (3), N-(3-triethoxysilanepropyl)-N, N-diacetic dimethylester (4), N-(3-trisodiumsilanolatepropyl)-N, N-diacetic acid disodium salt (5) and N-(3-trisodiumsilanolatepropyl)-ethylenediamine-N, N′, N′-triacetic acid trisodium salt (6). The reaction of silanes 1–4 with the silica was carried out under anhydrous conditions (procedure A). Silanes 1–6 were subjected to surface modification under essentially hydrous conditions applying a two-step procedure (procedure…
Impact of the post-treatment conditions of parent silica on the silanization of n-octadecyl bonded silica packings in reversed-phase high-performance…
2001
Native mesoporous silica beads were subjected to a sequence of post-treatment procedure including hydrochloric acid treatment, calcination and subsequent rehydroxylation. The post-treated silica beads were converted into RP-18 silica by silanization with monochloro- and dimethoxy-n-octadecylsilanes, respectively. The influence of post-treatments and silanization conditions on the physico-chemical characteristics and on the chromatographic behaviour of the RP-silicas was studied. Also the changes of the pore structural parameters and the silanol group densities during the post-treatment and silanization were assessed.
Separation of plasma membrane proteins of cultured human fibroblasts by affinity chromatography on bonded microparticulate silicas.
1984
Abstract Adsorbents for high-performance affinity chromatography were prepared by bonding proteins and reactive Procion triazine dyes to 3-isothiocyanatopropyl- and 3-aminopropylsilicas. The materials prepared were used successfully in the separation of hydrophobic plasma membrane proteins of cultured human fibroblasts. The data obtained show that the reaction of 3-isothiocyanatopropyltriethoxysilane (ITCPS) with the surface hydroxyl groups of silica yields a new and convenient route to preparing an “activated carrier” that is capable of coupling with potential affinity ligands containing amino functional groups. The reaction and bonding procedures of 3-isothiocyanatopropyltriethoxysilane a…
New Hybrid Organic-inorganic Multifunctional Materials Based on Polydopamine-like Chemistry
2021
Taking inspiration from the chemistry of dopamine, a simple and economic synthetic approach toward the synthesis of a series of silica-based polydopamine-like materials has been developed. Mild conditions and easy manipulation are the strongest aspects of this methodology. Such hybrid materials were successfully used as recyclable catalysts for Knoevenagel reactions.