The structure of DNA complexes with cationic liposomes-cylindrical or flat bilayers?

DNA complexes with cationic lipids promise to be versatile and effective synthetic transfection agents. Recent experiments identified both flat lamellar structures, where DNA strands are sandwiched between lipid bilayers, and cylindrical ones where the DNA is coated by a curved bilayer. Using a simple model we compare the stability of the two structures, and find that flat-bilayer aggregates are always more stable than the cylindrical ones. The different experimental observations are explained within the framework of the model predictions.