Particles hydroxyl-containing

This method is derived from that of Miron and Wilchek (1993) for the activation of hydroxyl groups on PEG molecules and Wilchek and Miron (1985) for the activation of agarose chromatography beads. Many types of hydroxyl-containing particles may be used in this procedure, provided that the solvent used for the activation step does not deleteriously affect particle integrity (Figure 14.16). 

Wash 100 mg of hydroxyl-containing particles 2 times using centrifugation with 0.1 M sodium carbonate, pH 8.5 (coupling buffer). After the second wash, resuspend the particles at 10 mg/ml in 2 M sodium carbonate (activation buffer no pH adjustment necessary). 

Figure 14.20 Particles containing reactive epoxy groups can be coupled with amine-, thiol-, or hydroxyl-containing molecules.

The Si02-X, SiOj-X, and SiOj-Y phases are hydroxyl-containing crystalline varieties of silica. The SiOj-X phase was obtained for the first time and is a well crystallized variety of Si02-X. The SiOj-Y phase, also obtained for the first time, is unlike any of the known silicate structures (Fig. 55). All these phases have a globular structure and particle size of the order of a few microns. According to infrared absorption spectra (Fig. 56), the structure of the intermediate phases is fairly disordered, with variable lattice parameters. 

To obtain highly stable polymer dispersions, the particles are usually provided with ionic groups, for example by adsorption of anionic or cationic surfactants, or by incorporation of ionic groups into the polymer. Another, nonionic type of stabilization takes place via hydrophilic groups on the particle surface, for example by amino-or hydroxyl-containing monomers or protective colloids. Polymer dispersions used in industry usually are stabilized by both mechanisms (ionic and nonionic). The special nature of the particle surface, which differs from the particle interior, plays an important role in all applications. 

Also present in the first test tube is a synthetic analog of ATP in which both the 2 and 3 hydroxyl groups have been replaced by hydrogens This compound is called 2 3 dideoxyadenosme triphosphate (ddATP) Similarly ddTTP is added to the second tube ddGTP to the third and ddCTP to the fourth Each tube also contains a primer The primer is a short section of the complementary DNA strand which has been labeled with a radioactive isotope of phosphorus ( P) When the electrophoresis gel is examined at the end of the experiment the positions of the DNAs formed by chain extension of the primer are located by a technique called autoradiography which detects the particles emitted by the P isotope... 

Clays are composed of extremely fine particles of clay minerals which are layer-type aluminum siUcates containing stmctural hydroxyl groups. In some clays, iron or magnesium substitutes for aluminum in the lattice, and alkahes and alkaline earths may be essential constituents in others. Clays may also contain varying amounts of nonclay minerals such as quart2 [14808-60-7] calcite [13397-26-7] feldspar [68476-25-5] and pyrite [1309-36-0]. Clay particles generally give well-defined x-ray diffraction patterns from which the mineral composition can readily be deterrnined. 

CuNPs) in Fig. 7 shows the monodisperse and uniformly distributed spherical particles of 10+5 nm diameter. The solution containing nanoparticles of silver was found to be transparent and stable for 6 months with no significant change in the surface plasmon and average particle size. However, in the absence of starch, the nanoparticles formed were observed to be immediately aggregated into black precipitate. The hydroxyl groups of the starch polymer act as passivation contacts for the stabilization of the metallic nanoparticles in the aqueous solution. The method can be extended for synthesis of various other metallic and bimetallic particles as well. 

DSC also is used to activate hydroxylic particles for coupling to amine-containing ligands (Miron and Wilchek, 1993). For methods involving particle conjugation using this homobifunctional compound, see Chapter 14. 

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