Dextrins matrices

Others,as well as hormones, may also be closed in dextrin matrices. The presence of dextrin provides the proper level of moisture in a given product. The additon of dextrin to pellets and the coatings of pellets makes these pharmaceuticals easily disintegrable under the influence of saliva or gastric acids. According to Indian workers, nondextrinized starch is a better binder than dextrin itself. 

Methylcyclopropene has also been prepared by reacting 3-chloro- or bromo-2-methylpropene with sodium amide or lithium di-isopropylamide in mineral oil and the product trapped in an a-dextrin matrix (3). In addition, it has been prepared in mineral oil using catalytic amounts of hexamethyldisilazane (4) as described below ... 

Often interfaces and colloids are discussed together. Colloids are disperse systems, in which one phase has dimensions in the order of 1 nm to 1 pm (see Fig. 1.1). The word colloid comes from the Greek word for glue and has been used the first time in 1861 by Graham1. He applied it to materials which seemed to dissolve but were not able to penetrate a membrane, such as albumin, starch, and dextrin. A dispersion is a two-phase system which is uniform on the macroscopic but not on the microscopic scale. It consists of grains or droplets of one phase in a matrix of the other phase. 

Another attempt is to prepare films with electronically isolated oligothiophene molecules in uniaxially oriented matrices. The matrix can consist of cyclic siloxanes [ 108] or dextrines which both possess cavities of defined diameter and length. Oligothiophenes can diffuse into the anisotropic matrix. Substitution with certain polar head-groups allows for a strong bonding to the metal substrate, i.e. nitriles or carboxyles couple to Pt, thiols to Au. 

This reaction has been modified extensively to proceed under different conditions. For example, it has been performed in liquid crystalline matrixes, sg in zeolite,in supercritical C02, on a silica gel surface, or in the presence of cyclo-dextrin. In addition, this reaction has been catalyzed by photoacid. Moreover, this reaction has been extended to various substrates other than the regular phenyl (or aryl) esters as described earlier. 

Surface plasmon resonance (SPR) is one of the most sophisticated methods these days for real-time detection and quantification of biomolecular interactions in a nondestructive fashion and without any labeling requirement [148]. SPR is based on the detection of binding pattern changes on a specific sensor surface caused by the interaction between the solute molecules in solution and the immobilized affinity components on the surface. Glass surfaces are coated by a matrix (e.g., dextrin) along with a conductive gold... 

Inoue et al, reported the intramolecular [4 + 4] photocycloaddition of 6A,6C-bis(2-anthracenecarboxylate) ester of a-cyclodextrin (a-CD) in water, which gave the antz-head-to-head cycloadduct (after base hydrolysis) in highly regio- and enantioselective manner in the presence of y-cyclo-dextrin (y-CD). " Diastereoselective photocyclodimers of ester of (249) tethered to cellulose were obtained. Saigo et al., found the diastereo- and enantio-selective photocyclodimerization of (249) and (250) by use of enantiopure amphiphilic amino alcohols as a matrix. The enantioselective photoreaction of (249) was also reported by Shinkai et al. (25Ia,b). 

Other Matrices. A large number of other matrices have been employed, including starch (33), cross-linked dextrins (34,35), a vinyl maleimide polymer (36), chitin (37), mannan (38), and insolubilized proteins (39). The number of potential matrices is almost limitless, and most of the matrices used for immobilization of enzymes have potential application in bioselective adsorption. Among these are nylon (40), metal oxides (41), maleic anhydride-ethylene co-polymers (42), and polystyrene derivatives (43). Few of these have been used because of their potential for nonspecific adsorption either by charge, as with the metal oxides, or by hydrophobic interactions (as would be the case with polystyrene). The derivatized matrix must be free of nonspecific adsorption. Proper derivatization can eliminate nonspecific adsorption or, as with cyanogen bromide activation, create nonspecific adsorption in matrices having no prior nonspecific adsorption properties. 

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