Poly -dextran

Plant polyphenols Weakly and medium basic anion exchanger celluloses and poly-dextran Nagels et al. [416]... 

Poly(dextran-g-(l-amidoethylene))) dextran-acrylamide graft copol3rmer... 

Reaction Parameters for the Preparation of Poly(Dextran-g-l-amidoethylene),... 

Effects of Variation Ce(lV) Concentration on the Resulting Poly(Dextran-g-... 

Poly(dextran-g-acrylamides) from ceric ion initiation (2) Dextran-g-acrylamide copolymers were prepared by ceric ion initiation in water at 25 C using 0.05 M nitric acid. The reactions were conducted for three hours with an initial dextran concentration of 0.0617 M (moles of glucose units) and an acrylamide concentration of l.OM. The molecular weight of the dextran obtained from ICN Pharmaceuticals, Inc. was reported to be = 200,000 to 300,000. Ceric ion concentrations were varied from 2.5 x 10" moles/liter to 10.0 x 10 moles/liter. 

Poly(dextran-g-acrylamides) from ferrous ion—hydrogen peroxide initiation Graft copolymerization of acrylamide onto dextran with ferrous ion-hydrogen peroxide initiation is being studied in detail. The effect of variation of each reaction parameter on graft copolymerization behavior may be measured by direct gel permeation chromatographic analysis of the final product polymer solution. 

Table 6. Viscosity Data for Poly(dextran-g-acrylamide) Samples in 1.5% NaCl Solution at 30 C ...

Two-Phase Aqueous Extraction. Liquid—Hquid extraction usually involves an aqueous phase and an organic phase, but systems having two or more aqueous phases can also be formed from solutions of mutually incompatible polymers such as poly(ethylene glycol) (PEG) or dextran. A system having as many as 18 aqueous phases in equiHbrium has been demonstrated (93). Two-phase aqueous extraction, particularly useful in purifying biological species such as proteins (qv) and enzymes, can also be carried out in combination with fermentation (qv) so that the fermentation product is extracted as it is formed (94). 

Cationic hydrophilic Glycol chitosan, DEAE-dextran, poly(ethyleneimine), poly(trimethylaminoethyl methacrylate) iodide salt 0.5 M acetic acid with 0.3 M NaiSO, or 0.8 M NaNO.,... 

The GBR resin works well for nonionic and certain ionic polymers such as various native and derivatized starches, including sodium carboxymethylcel-lulose, methylcellulose, dextrans, carrageenans, hydroxypropyl methylcellu-lose, cellulose sulfate, and pullulans. GBR columns can be used in virtually any solvent or mixture of solvents from hexane to 1 M NaOH as long as they are miscible. Using sulfonated PDVB gels, mixtures of methanol and 0.1 M Na acetate will run many polar ionic-type polymers such as poly-2-acrylamido-2-methyl-l-propanesulfonic acid, polystyrene sulfonic acids, and poly aniline/ polystyrene sulfonic acid. Sulfonated columns can also be used with water glacial acetic acid mixtures, typically 90/10 (v/v). Polyacrylic acids run well on sulfonated gels in 0.2 M NaAc, pH 7.75. 

Commercial narrow standards [such as poly(ethylene glycol) (pEG), polystyrene sulfonate, pAA, poly w-vinyl pyrrolidinone, dextrans] are available from American Polymer Standards Corporation, Polymer Laboratories, Polymer Standards Service USA, Toyo Soda, and others. While these standards are often not as narrow as pSty or pMMA that has been anionically polymerized, they are acceptable for narrow standard calibrations. 

Recently, Brich and coworkers (40) reported the synthesis of lactide/glycolide polymers branched with different polyols. Polyvinyl-alcohol and dextran acetate were used to afford polymers exhibiting degradation profiles significantly different from that of linear poly-lactides. The biphasic release profile often observed with the linear polyesters was smoothened somewhat to a monophasic profile. Further, the overall degradation rate is accelerated. It was speculated that these polymers can potentially afford more uniform drug release kinetics. This potential has not yet been fully demonstrated. 

Fig. 3 Polypeptide vesicle with endocytosis capability, (a) Vesicles formed from poly(L-arginme)6o-h-poly(L-leucme)2o- The poly(L-arginme) block provides an added cell-penetrating feature to the vesicles, (b, c) LCSM images of internalized vesicles (green) containing Texas-Red-labeled dextran (red) in (b) epithelial and (c) endothelial cells. Colocalization of the vesicles and Texas-Red-labeled dextran appears as a yellow fluorescent signal. Adapted from [44] with permission.Copyright 2007 Macmillan Publishers...

Some antigens, such as type 3 pneumococcal polysaccharide, EPS and other polymeric substances such as dextrans (poly-D-glucose) and levan (poly-D-fructose) can induce antibody synthesis without the assistance of TH cells. These are known as T-independent (Ti) antigens. Only one class of immunoglobulin (IgM) is synthesized and there is a weak memory response. 

Dextran is the collective name of extracellular bacterial poly-alpha-D-glucopyranoses linked largely by 1,6 bonds, with branching occurring at the 1,2, 1,3 or 1,4 bonds. Physical properties vary... 

Amino acids used include Gly, Ala, Phe, Leu, His, co-aminoheptanoic acid, and Ala-His dipeptide. It was found that not only single amino acids were added to the dextran, but also poly(amino acid) chains formed during the reaction. 

Figure 17 Permeability of uranine ( ), dextran 4.4K (O), and dextran 150K (A) through cross-linked poly(/V-isopropyl acrylamide-co-butyl methacrylate, 95 5 mol%) membrane. Error bars represent standard deviation in the slope of the curve of the receiver concentration of solute as a function of time at steady state. (From Ref. 37.)...

---