title: The ionic strength effect on the DNA complexation by DOPC - gemini surfactants liposomes.
abstract: Liposome dispersions obtained from the mixture of gemini surfactants of the type alkane-α,ω-diyl-bis(alkyldimethylammonium bromide) and helper lipid DOPC create complexes with DNA showing a regular inner microstructure, identified by small angle X-ray diffraction as condensed lamellar phase (L(α)(c)). In addition to the L(α)(c) phase, a coexisting lamellar phase L(B) was also identified in the complexes formed, with periodicities in the range ~8.8-5.7nm, at ionic strengths corresponding to 50-200mM NaCl. The periodicities of L(B) phase did not correspond to those identified in liposome dispersion without DNA using small angle neutron scattering. The observed phase separation is shown to depend on the interplay between the surface charge density of cationic liposomes, ionic strength and method of complex preparation. The effect of ionic strength on complex formation was studied by isothermal titration calorimetry and zeta potential measurements. High ionic strength reduces the fraction of bound DNA in the complexes, and the isoelectric point is attained at a ratio of DNA/gemini surfactant which is lower than the one that can be estimated by calculation based on nominal charges of CLs and DNA.
authors: Department of Physical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, SK-812 37 Bratislava, Slovakia. pullmannova@fpharm.uniba.sk
authors: Petra
authors: P
authors: Pullmannová
authors: Margarida
authors: M
authors: Bastos
authors: Guangyue
authors: G
authors: Bai
authors: Sergio S
authors: SS
authors: Funari
authors: Ivan
authors: I
authors: Lacko
authors: Ferdinand
authors: F
authors: Devínsky
authors: José
authors: J
authors: Teixeira
authors: Daniela
authors: D
authors: Uhríková
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000031:analogs & derivatives* / Q000737:chemistry; D002417:Cattle; D004247:DNA / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D009994:Osmolar Concentration; D010713:Phosphatidylcholines / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: C411462:1,25-dihydroxy-21-(3-hydroxy-3-methylbutyl)vitamin D(3); D008081:Liposomes; D010713:Phosphatidylcholines; D013501:Surface-Active Agents; D004247:DNA; C427203:calf thymus DNA; C017251:1,2-oleoylphosphatidylcholine; D002117:Calcitriol