title: The structure of DNA-DLPC-cationic gemini surfactant aggregates: a small angle synchrotron X-ray diffraction study.
abstract: The structure of aggregates formed by interaction of DNA with unilamellar dilauroylphosphatidylcholine (DLPC) vesicles (DNA:DLPC=1:1 base/mol) in the presence of gemini surfactant butane-1,4-diyl-bis(dodecyldimethylammonium bromide) (C12GS) was investigated using synchrotron small angle X-ray diffraction. In the concentration range C12GS+:DLPC< or =1 mol/mol, a condensed lamellar Lalphac phase was found with a repeat period of lipid bilayer stacking in the range d approximately 5.70-6.53 nm and the DNA interhelical distance d(DNA) approximately 3.52-3.99 nm, depending on the concentration of C12GS. At molar ratio C12GS+:DLPC> or =0.35:1, the diffractograms have shown the presence of a second lamellar phase with the repeat period d approximately 5.31 nm which slightly decreases with increasing concentration of C12GS+. The increasing fraction of this phase in the aggregates with increasing concentration of C12GS supports the association of this phase with microscopic domains enriched by surfactant molecules. The temperature behaviour of aggregates was investigated in the range 25-60 degrees C and the transversal thermal expansivities of the observed phases were determined.
authors.affiliation: Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University, Odbojárov 10, 832 32 Bratislava, Slovakia. daniela.uhrikova@fpharm.uniba.sk
authors.forename: Daniela
authors.initials: D
authors.lastname: Uhríková
authors.forename: Mária
authors.initials: M
authors.lastname: Hanulová
authors.forename: Sérgio S
authors.initials: SS
authors.lastname: Funari
authors.forename: Ivan
authors.initials: I
authors.lastname: Lacko
authors.forename: Ferdinand
authors.initials: F
authors.lastname: Devínsky
authors.forename: Pavol
authors.initials: P
authors.lastname: Balgavý
mesh_terms: D002082:Butylamines / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry; D008956:Models, Chemical; D015233:Models, Statistical; D010713:Phosphatidylcholines / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D017356:Synchrotrons; D013696:Temperature; D013816:Thermodynamics; D014961:X-Ray Diffraction
chemical_list: D002082:Butylamines; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; C500728:butane-1,4-diylbis(dodecyldimethylammonium bromide); C015153:1,2-dilauroylphosphatidylcholine; D004247:DNA