Self-assembly of cationic liposomes–DNA complexes: a structural and thermodynamic study by EDXD

We report a comprehensive study of the lamellar dioleoyl trimethylammonium propane and DNA complexes (DOTAP–DNA) as a function of the lipid/DNA weight ratio ρ in order to determine their structure and thermodynamic stability using an energy dispersive X-ray diffraction technique (EDXD). These self-assemblies consist of a periodic multilayer structure with DNA chains adsorbed between cationic membranes. Furthermore, above and below the isoelectric point, the DNA packing density significantly varies as a function of ρ. Our results confirm that EDXD is a powerful technique to characterize self-assembled ordered structures of oppositely charged macromolecules.