Dextran sulfonated

The major route to colloidal (effectively water soluble) PAn has been through the chemical oxidation (S2082-) of the monomer in the presence of polymeric steric stabilizers and electrosteric stabilizers (polyelectrolytes), such as poly(vinyl alcohol), polyGV-vinyl pyrrolidone), polyethylene oxide), polystyrene sulfonate), dodecylben-zene sulfonate, and dextran sulfonate. It has been found that the stabilizer can act simultaneously as a dopant, imparting new functionality to the polymer or additional compatibility for the final application. 

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. 

SP Sephadex C-25 cation exchangers whose dextran support, itself composed of propane-sulfonate-functionalized cross-hnked a-o-glucopyra-noside units, provides the chiral environment. Thus chiral eluents are not always necessary and achiral solvents can be used for separation. However, in some cases, separation is improved using an eluent containing a chiral ion [13]. 

Starch esters have been obtained by reactions of starch and carboxylic or sulfonic acid imidazolides in aqueous NaOH or nonaqueous solutions, as described in reference [226]. The esterification of dextran with butyric or palmitic acid using CDI in DMSO or formamide is discussed in reference [174]. 

Quench the reaction by immediate gel filtration on a desalting column. If a dextran-based resin is used for the chromatography, the support itself will react with sodium periodate to quench excess reagent. Alternatively, N-acetylmethionine may be added to quench the reaction, because the thioether of the methionine side chain will react with periodate to form sulfoxide or sulfone products (Geoghegan and Stroh, 1992). In addition, sodium... 

Significant research has been directed toward the use of polyelectrolyte complexes as blood compatible materials. Several investigators found that water-insoluble polyelectrolyte complexes can suppress blood coagulation [487-490]. Davison and coworkers reviewed and studied the biological properties of water-soluble polyelectrolyte complexes [491] between quatemized poly(vinyl imidazole) or polyvinyl pyridine) and excess sulfonated dextran or poly(methacrylic acid). By forming complexes with a stoichiometric excess of anionic charge, a more compact conformation with anionic character was obtained. 

Finally, the hetero polysaccharide hexagluconylhexasaminoglycan sulfate was identified as an anticoagulant and antithrombotic material compared to heparin by Sederel and coworkers [521], Derivatives of the polysaccharide dextran containing sulfate, sulfonate or carboxylic groups gave antithrombotic activity due to the presence of these charged groups [483, 522-525],... 

Figure 13.4. Apparent MWs of HS from different environments as determined by SEC [compiled from the data reported by Perminova et al. (2003)]. Bars represent a range of weight-averaged molecular weights determined for different groups of humic materials. Two black dots represent two IHSS standards Suwannee River FA and HA. SEC chromatograms were obtained with column-packing Toyopearl HW-50S using 0.028 M phosphate buffer at pH 6.8 as a mobile phase. Two different sets of standards were used to calibrate the column polystyrene sulfonates (PSS) and polydextrans the upper MW scale corresponds to dextran calibration and the bottom one—to PSS calibration.

Via the in situ activation, applying sulfonic acid chlorides, covalent binding of bioactive molecules onto dextran was achieved by esterification of the polymer with a-naphthylacetic acid (1), nicotinic acid (2) and naproxen (3) homogeneously in DMF/LiCl using p-toluenesulfonyl chloride (tosyl chloride, TosCl) or methanesulfonic acid chloride (mesyl chloride, MesCl) and pyridine within 22 h at 30-70 °C (Fig. 22). 

Table 8 Influence of the concentration of pyridine [Py], the reaction temperature, and type of sulfonic acid chloride applied for the esterification of dextran (0.12 mol L 1) in DMF/LiCl with a-naphthylacetic acid (0.37 mol L-1) for 22 h...

Table 14 Composition, anticoagulant (antithrombic), and anticomplementary activities of dextran derivatives with different DS of carboxymethyl (CM), benzylamide (B) and sulfonate/sulfate (S) functions ...

The synthesis of CMDBSSu involves the random carboxymethylation of hydroxyl groups on the glucose units, the benzylamidation of some of the carboxylic groups with benzylamine in the presence of N-ethoxycarbonyl-2-ethoxy-l,2-dihydroquinoline (EEDQ) to carboxymethyl dextran benzylamide (CMDB), the sulfonation of phenyl rings and sulfation of remaining hydroxyl groups at the polymer backbone (Fig. 39, [108,222]). 

Fig. 39 Synthesis of carboxymethyl dextran sulfate (CMDSu), carboxymethyl dextran ben-zylamide sulfate (CMDBSu) and carboxymethyl dextran benzylamide sulfonate sulfate (CMDBSSu), respectively...

Water-insoluble PEC were prepared by mixing oppositely charged polyelectrolytes, e.g. DEAE dextran with CMD [340,341], sodium dextran sulfate, poly(styrene sulfonate) (NaSS) [342], poly(sodium L-glutamate) (PSLG), poly(vinyl alcohol)sulfate [343], or potassium metaphosphate (MPK) [240]. They are useful as membranes or in biomedical applications [343,344]. 

Matrex PAE-300 (silica based, polyethyleneimine coated weak anion exchange, 10 fi particles) dextran sulfate (MW 5-500 kD), polyvinyl sulfonic acid (MW 2kD) /3-lactoglobulins A and B 30, 31... 

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