Wormlike lipid/DNA micelles in a non-polar solvent
Geschwister-Scholl-Platz 1, Ludwig-Maximilians-Universität, D-80539, München, Germany
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Accepted: 20 September 2006
Published online: 16 October 2006
The phase behavior of DOPE/DOTAP-DNA complexes in phase-separated oil(dodecane)/water mixtures was explored using Small Angle X-Ray Scattering (SAXS) and Fluorescence Correlation Spectroscopy (FCS). Inverse micelles of DNA with cationic-lipid coating were found in the oil phase. Varying the ratio between cationic and neutral lipids a transition from wormlike to spherical structures is observed for both long ( ≈ 75000bp) and short (30-1246bp) DNA. In contrast to lipid/DNA complexes in the water phase, there is no indication of condensed liquid-crystalline structures in the non-polar phase. In fact, FCS measurements on short DNA oligomers complexed with cationic lipid in alkane give clear evidence for monomeric inverse micelles of DNA. Dilution series revealed a critical lower concentration of lipids and DNA for observing lipid/DNA micelles.
PACS: 83.80.Qr Surfactant and micellar systems, associated polymers – / 87.14.Cc Lipids – / 87.14.Gg DNA, RNA – / 87.64.Bx Electron, neutron and X-ray diffraction and scattering –
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2006