Silanization procedures

In general, the silanization of hydroxyl-terminated substrates such as silica or glass is an effective method which is used quite often for chemical modification of the substrate surface for immobilization of biomolecules. The main focus for silanization procedures is once again the examination of the self-organizing silane-monolayers. The properties of the monolayer depend on the chemical structure of the silanization reagent, the density of silanol-groups which are available on the surface and the physical surface structure on a nano-scale level. 

Flowever, the focus of the major part of the chapters lies on the couphng chemistry used for DNA immobilization. Successful immobihzation techniques for DNA appear to either involve a multi-site attachment of DNA (preferentially by electrochemical and/or physical adsorption) or a single-point attachment of DNA (mainly by surface activation and covalent immobihzation or (strept)avidin-biotin linkage). Immobilization methods described here comprise physical or electrochemical adsorption, cross-linking or entrapment in polymeric films, (strept)avidin-biotin complexation, a surface activation via self-assembled monolayers using thiol linker chemistry or silanization procedures, and finally covalent coupling strategies. 

FIGURE 1.3 Schematic representation of the silanization procedure of borosilicate or fused silica capillary column inner walls, (a) Surface etching under alkaline conditions, (b) attachment of reactive groups by condensation with silanol, (c) chemical linkage of polymer (PS/DVB considered as example) by free radical polymerization. 

Fig. 4 Mach-Zehnder interferometer for classical interferometry. Here, one arm, the grey one, is functionalized with AuNPs to allow for a thiol surface functionalization for an immunoreaction, instead of a silanization procedure...

Another silanization procedure for the derivatization of carbohydrates is the formation of trimethylsilyl oximes. The methyloxime is heated with hexarnethyl-disilazane trifluoroacetic anhydride (9 1 v/v) for 1 h at 100°C. Anthrone O-glucoside is an important ingredient in skin care cosmetics and can be fully silylated by reaction with A/,0-bistrimethylsilylacetamide acetonitrile mixture (1 1 v/v) for 1 h at 90°C, and subsequently separated by GC. 

Depending on the concentration of DNA used in the sample preparation procedure, the surface coverage can be adjusted. The fixation using the silanization procedure is beneficial in effectively immobilizing the DAN for AFM work. Stability in excess of 5 h has been reported [106] (Fig. 3.50). 

Previous communications 1,2) have described the determination of reactive hydroxyls and total hydroxyls on a silica surface by silanization procedures. Reactive hydroxyls 5, (milliequivalents per gram) are determined by selective silanization with trimethylchlorosilanet (TMCS), and total hydroxyls (milliequivalents per gram) are determined by complete... 

Fig. 2. Scheme cf a polyfunctional brandling point and of a part of network of a pdyolefin crosslinked through the silane procedure... 

Cracking of polypropylene at 360°C over hierarchical and ZSM-5 zeolites, both obtained by a seed silanization procedure [165]. The improved accessibility of these hierarchical catalysts for bulky polypropylene molecules resulted in a fourfold greater conversion than conventional zeolites. 

Now we analyze the trends in Fig. 5 in two steps (1) the silanization procedure in toluene solution and (2) contact angle measurement in an aqueous environment and their surface energies. In the n = I case, silane molecules can bind to reactive sites on the surfaces in a densely packed state but probably patchy style, due to the three bulky methyl groups per silane molecule. 

Another brief exposure was performed with 1% organosilane in benzene at 6 C under argon for 10 s. A more aggressive silanization procedure was used to modify glass with neat organosilane in a sealed tube at 90 C for 12 h. The authors evaluated their films via XPS to determine thickness and approximate surface coverages. 

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