Stability of DNA-containing interpolyelectrolyte complexes in water-salt solutionsстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:Destruction of interpolyelectrolyte complexes (PEC) formed by DNA and different poly(N-alkyl-4-vinylpyridinium) cations was achieved by addition of low molecular weight electrolytes. Monitoring of PEC dissociation was carried out by fluorescence quenching using the ability of the cationic dye ethidium bromide to intercalate into free sites of the DNA double helix accompanied by fluorescence. Degree of polymerization and charge density of the polycations as well as their N-alkyl substituentes (alkyl = methyl, ethyl, and propyl) were shown to be factors influencing the stability of PEC. The ability of added cations and anions to dissociate PEC decreases in the order Ca++ > Mg++ >> Li+ > Na+ > K+ > (CH3)4N+ and I– > Br– > Cl– >> F– which coincides with a decrease of affinity of the same counterions to DNA and to the polycation. The data obtained indicate that the change of the stability of DNA-containing PEC shows the same regularities as revealed for the stability of interpolyelectrolyte complexes formed by oppositely charged flexible synthetic polyelectrolytes in water-salt solutions.