Eur. Phys. J. E (2006) 21: 41-48
https://doi.org/10.1140/epje/i2006-10043-y

Regular Article

Wormlike lipid/DNA micelles in a non-polar solvent

Geschwister-Scholl-Platz 1, Ludwig-Maximilians-Universität, D-80539, München, Germany

^* e-mail: joachim.raedler@physik.uni-muenchen.de

Received: 13 January 2006
Accepted: 20 September 2006
Published online: 16 October 2006

Abstract

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.