Dextran polyanionic

TiTany commercial uses of carbohydrates depend upon reversible inter- actions of the hydroxyl groups with ions to form complexes. The processes are intricate, and analyses of the equilibria involved have been difficult or impossible (I). For example, the nature of the complexes involving polysaccharides and polyanions, such as borate, can only be hypothesized (2). Similarly the gelling of pectates with Ca(II) (3), the reactions of heptono-y-lactones with Fe(III), or the nature of Fe(III)-dextran complexes in intramuscular injectable solutions are awaiting proper description. Although the systems involving monomeric components are more amenable to study, as for the reactions of metal salts or hydroxides with monosaccharides or their simple derivatives (4,5, 6, 7)... 

Polyanion precipitation has been used for separating apo-B-containing lipoproteins from other lipoproteins. Gidez et al. (G4) have used a fractional precipitation procedure with dextran sulfate and Mn2+ to precipitate apoB-containing lipoproteins first, then HDL2. 

OptiMEM I reduced-serum medium is widely used for complex formation. Other serum-free media can also be used as long as they are free of polyanions such as heparin or dextran-sulfate, which compete with DNA or nucleic acids to bind to the transfection reagent. 

A recent study has explored the potential of the ternary complex formed between a poly(p-cyclodextrin) (formed by polycondensation of p-cyclodextrin), a cationic surfactant (dodecyltrimethylammonium chloride), and a polyanion in water, to act as a delivery system for gene therapy,using a combination of viscometric and SANS studies as well as visual observations to determine the macroscopic and microscopic properties of the complexes. In the study, sodium dextran sulfate was used as a substitute for DNA. The potential advantages of the use of such ternary complexes over the more commonly investigated DNA-lipid or polymer complexes (lipoplexes and poly-plexes, respectively) include a high water solubility of the resulting complex (lipoplexes and polyplexes often... 

A second structural feature for interferon induction by polycarboxylates is the presence of negative charges. They may be placed in either alternate (PAA) or adjacent (pyran copolymer) position but should occur in a regular and dense sequence. The polyanionic character of the polymer appears to be a prerequisite for interferon induction, antiviral activity and antibacterial activity, since uncharged polymers such as dextran, polyacrylamide, non-carboxylated polyethylene analogues of pyran copolymers and incompletely oxidized amylose were devoid of any of these activities48,49,51,107). 

Heparin (50 mg in 4 X SSPE or 4 X SSC) is also used as blocking agent at 50 [xg/ml or at 500 xg/ml if dextran sulfate is present (Singh and Jones, 1984). Lebacq et al. (1988) observed that heparin (a polyanionic mucopolysaccharide) lowered the general background significantly on positively charged nylon when used at 3.5 mg/ml. 

Mattai J, Kwak JCT. Binding of La3+ ions by dextran sulfate polyanions in aqueous solutions containing excess sodium chloride. J Phys Chem 1984 88 2625-2629. 

Kimberlin, R.H., and Walker, C.A. (1986). Suppression of scrapie infection in mice by hetero- polyanion 23, dextran sulfate, and some other polyanions. Antimicrob. Agents Chemother. 30, 409-413. 

Newer 2-diethylaminoethyl ethers, such as 0-( 2-diethylaminoethyl )-agarose gels," are useful as media for electrophoresis and immunoelec-trophoresis, and the 2-diethylaminoethyl derivative of O-(2-hydroxy-propyl ) cross-linked dextran (Sephadex LH20) is an effective, lipophilic anion-exchanger. The relative stiffness of the molecular chain of 0-(2-diethylaminoethyl) dextran has been estimated from measurements of viscosity at various ionic strengths, and compared with that of other polysaccharide polycations and polyanions. 0-(2-Diethylaminoethyl) dextran itself is claimed to be toxic." ... 

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