Silane Compound Research Articles

High-Efficiency Solid-Phase Capture Using Glass Beads Bonded to Microcentrifuge Tubes: Immunoprecipitation of Proteins from Cell Extracts and Assessment of Ras Activation

We have bonded glass microbeads (425–600 μm diameter) to the inner walls of polypropylene microcentrifuge tubes. In addition to increasing the surface area of the tubes manyfold, the beads provide surface Si groups which can be reacted with a silane compound such as aminopropyltriethoxysilane, yielding a free amino group. The amino group is reacted with another cross-linking reagent, for example, the homobifunctional compound dimethyl suberimidate, which can form a covalent bond with amine groups of proteins. After binding protein A or G to the dimethyl suberimidate, the beads were used to immunoprecipitate proteins from cell extracts; we show that the protein A/G-coated glass beads yield similar amounts of immunoprecipitated proteins as a standard method using protein A– or G–agarose beads, but with fewer contaminating proteins. In addition, we show that when immunoprecipitating Ras from cell extracts and measuring the amounts of Ras-bound GTP and GDP, the new method yielded higher guanine nucleotide levels than protein G–agarose beads, suggesting that it caused less denaturation of Ras. Because the glass beads are bonded to the walls of the tubes, the immunoprecipitates can be washed rapidly and efficiently, and we show that 20–30 tubes can be washed in 1/10 the time required to wash immunoprecipitates on protein A– or G–agarose beads.

Dissociative ionization of halogenated ethylenes in intense femtosecond laser pulses

The interaction of chloro-ethylene (H 2CCHCl), bromo-ethylene (H 2CCHBr), and 2-chloro-ethenylsilane (H 3SiCHCHCl) with 50 fs linearly polarized laser pulses of 800 and 400 nm at intensities up to 2×10 14 and 7×10 12 W cm −2 , respectively, has been studied using a time-of-flight mass spectrometer. At 400 nm extensive fragmentation is observed, while at 800 nm the presence of singly and doubly charged parent ions and of multiply charged atomic ions in the mass spectra attests to a reduction of fragmentation in favour of multiple ionization of the parent followed by Coulomb explosion. The silane compound dissociates more easily, its multicharged atomic fragments appear at lower intensities and are ejected with higher kinetic energies than the chlorine and bromine derivatives. The results reveal that laser–molecule coupling is influenced by the molecular properties and that energy channeling increases with molecular size.

DNA extraction using modified bacterial magnetic particles in the presence of amino silane compound

Magnetic particles produced by magnetic bacteria have been used to carry out magnetic separation of DNA. Separation was achieved using magnetite coated with 3-aminopropyltriethoxysilane, N-(trimethoxy-silylpropyl) isothiouronium chloride or 3-[2-(2-aminoethyl)-ethylamino]-propyltrimethoxysilane (AEEA). The DNA binding efficiency increased with the number of amino groups present on the silane compounds and was 14 fold higher than with untreated magnetite. Addition of AEEA to aqueous solutions containing coated magnetite increased efficiency due to co-condensation of DNA. From 10 8 Escherichia coli cells, 7.1 μg of DNA was recovered using 100 μg of magnetite. E. coli DNA extracted with modified bacterial magnetite was suitable for restriction enzyme digestion and polymerase chain reaction (PCR). Ten replicate samples of E. coli cells were extracted using an automated magnetic robot and 9.5 μg of DNA was extracted using 100 μg of modified bacterial magnetite and possessed a 1.94 absorbance ratio (260:280 nm).

Free radical hydrosilylation of polypropylene

Hydrosilylation of terminal double bonds in polypropylene was investigated via a free radical process in the melt-phase. This process involved the following two reactions occurring in parallel: chain scission, which leads to formation of double bonds, and the addition of silyl radicals to such bonds. Fourier Transform Infrared Spectrometry (FT–IR) was used to follow silane incorporation and terminal double bond formation. The experimental trends were verified using elemental analysis obtained from energy dispersive x-ray analysis (EDX). Using a single screw extruder and a model silane compound, a 23 full factorial experiment design was implemented with the following investigated factors: residence time, silane concentration, and peroxide concentration. Statistical analysis of the FT–IR results, showed that, for the silane incorporation, residence time, peroxide concentration, and the interaction between the silane and peroxide concentrations had significant effects. The significant effects for the forma-tion of terminal double bonds were residence time, silane concentration, and peroxide concentration. The experimental results have shown that melt-phase hydrosilyla-tion of polypropylene can be accomplished through this noncatalytic free radical method. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:439–447, 1997

Interaction of Silane Coupling Agents with CaCO3

A study of eight silane coupling agents showed very different effect of these compounds on the mechanical properties of PP/CaCO3composites. The application of aminofunctional silane coupling agents resulted in the reactive coupling of the two inactive components leading to increased strength and decreased deformability. A detailed study of the interaction between CaCO3and the various coupling agents was carried out in order to find an explanation for the strong coupling effect. The amount of coupling agent creating a monolayer coverage was determined by a dissolution method for each coupling agent. The obtained values changed between 0.3 and 1.0 wt% calculated for the CaCO3. An attempt was made to determine the orientation of the adsorbed molecules to the filler surface. Most of the coupling agents are oriented perpendicularly to the surface with the exception of a methacryl functional silane compound. Possible interactions between hydrolyzed or condensed silane coupling agents and the filler were studied by Fourier transform infrared spectroscopy using transmitting (FTIR-TS) and diffuse reflectance (DRIFT) modes, as well as gel permeation chromatography (GPC). The results showed that bulky organofunctional groups form a caged, polycyclic, low-molecular-weight structure on the surface, while silanes with smaller groups tend to condense into open, ladder type, high-molecular-weight polysiloxane chains. Polymer/filler adhesion, however, depends primarily on the chemical character of the organofunctional group. Aminofunctional silane coupling agents adhere well to the filler surface and react also with the polymer. In the case of similar functionality the size of the organofunctional group determines the strength of the adhesion.

On the structure of bis(9-fluorenyl)dimethylsilane: a sterically crowded molecule with relatively low barriers of rotations around the Si−C(fluorenyl) bonds X-ray diffraction analysis and AM1 molecular orbital calculations

The X-ray structure of bis(9-fluorenyl)dimethylsilane, the first silane compound containing two voluminous fluorenyl groups, has been determined. The crystal system is orthorhombic with Aba2 space group. The unit cell ( a = 18.672, b = 36.089, c = 12.802 Å) contains two sets of four molecules, each one of one set being symmetrically related with the others of the same set. The conformations around the IIC(fluorenyl)SiC(fluorenyl) bonds may be grossly described as in-in, in-out and out-out. The AM1 calculations have shown that the barrier between the in-out and in-in conformations is relatively low while that between the in-out and out-out is higher; thus, probably, the first two are the most populated in solution. These results provide a better understanding of some unusual chemical shifts previously observed in 1H-NMR for Me 2Si(CHR 2) 2 and Me 2Si(CHR 2)(CR′R 2).

Contact allergy to allergy to allyl glycidyl ether present as an impurity in 3‐glycidyloxypropyltrimethoxysilane, a fixing additive in silicone and polyurethane resins

We present a 43-year-old man who worked in the plastics industry and who suffered from an occupational dermatitis on the hands and forearms. He was found to be allergic to an epoxy silane compound that was contaminated with allyl glycidyl ether, a reactive epoxy diluent. HPLC analysis and patch testing indicated that this impurity was probably the only sensitizer. Moreover, the gloves used provided absolutely no protection, as the inner side also generated strong positive reactions.

Copolymerization of propene and butadiene with MgCl2 supported titanium catalytic systems

AbstractUpon copolymerization of propene and butadiene, using the recent generation of high mileage stereospecific MgCl2 supported TiCl4AIR3 catalytic systems, it is possible to incorporate a small proportion of butadiene units in polypropene, keeping reasonable, although strongly reduced, activity. The isospecificity of the catalysts for the propene polymerization is not affected, and even may be improved upon butadiene incorporation. The butadiene is incorporated in blocks of trans‐1,4 units. The amount of incorporation is dependent on the temperature, on the presence and then on the nature and concentration of a silane compound as an external Lewis base, and also on the nature of the alkylaluminium cocatalyst. The silane causes a small amount of 1,2‐butadiene units to be incorporated. The molecular weights of the polymers are strongly decreased but the crystallinity is only slightly affected.

Silanized Polyaniline as an Electrochromic Material

An electrochromic film of polyaniline was electropolymerized from an acidic aqueous solution on a fluorine‐doped, glass precoated with an aniline derivative of a silane compound. The silane layer acted as a coupling agent to improve the surface adhesion of the electrochromic polyaniline film. The silanized polyaniline was found to possess good electrochromic properties, becoming blue upon electrochemical oxidation and near transparent upon reduction. The aging characteristics of the polyaniline film were found to be improved upon silanization.

Controlled porous glass (CPG) with reactive epoxy groups as support for affinity chromatography I. Optimization of CPG modification and the binding of glucose with modified surface

AbstractThe selective and complementary interaction between the ligand bound to support surface and isolated substance is the key of the affinity chromatography. This is the reason of the research in the field of certain sorbents. They are obtained by chemical reaction of matrix with proper ligands. It is carried out mainly by using bifunctional substances which make the reaction with the ligand in question possible. This paper deals with the preparation of controlled porosity glass with reactive epoxy groups. In order to obtain such support and avoid application of a proper epoxy silane compound, the double‐step reaction using simple agents was employed. The sorbent syntheses were optimized. The prepared sorbents were applied for coupling some carbohydrates and amino acids.

An analysis of the thermal decomposition of tetraethoxysilane by gas chromatography

The principle products of the thermal decomposition of tetraethoxysilane in a flowing system are acetaldehyde, ethanol, ethylene, and ethane. Acetal is found as a secondary reaction product formed by the addition of collected ethanol to acetaldehyde. Although the same products are produced by the thermal decomposition of diethyl ether at the same temperature, no ether has heen found in the reaction products of the silane compound. The products are probably derived directly from the silane molecule.