Structure of in-serum transfecting DNA-cationic lipid complexes.

Noticeable modifications of in-serum transfection efficiency of dioctadecylamidoglycyl-spermine (DOGS)-DNA complexes are observed, depending on DNA condensation conditions. The structures of the complexes are studied, keeping in mind the variability of lipid polymorphism, by cryo-transmission electron microscopy and X-ray diffraction. By increasing both pH and ionic strength, well-organised lamellar structures with a period of 65 A replace supramicellar aggregates. A relationship between the structures and their in-vitro transfection activity is established. Efficiency in the presence of serum is maintained when a lamellar arrangement is involved.