Berlin 2001 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 8: Biological Systems

CPP 8.1: Talk

Wednesday, April 4, 2001, 15:45–16:05, 111

Structural characterization of polycation/lipid/DNA complexes — •Armelle B.E. Vix and Joachim O. Rädler — MPI for Polymer Research,Ackermannweg 10,55128 Mainz,Germany

Cationic liposomes are efficient synthetic gene carriers with potential application in human gene therapy. The use of polycation/cationic lipid mixtures like protamine in addition to the cationic lipids yields smaller and more stable gene transfer particules when complexed with negatively charged DNA. The transfer efficiency strongly depends on the structure of the complexes built by three components, namely lipids, protamine and DNA. From the internal structure of these complexes, information can be obtained about the balance of the self-assembling forces existing in the composites. We are investigating the complexes by Small Angle X-ray Scattering as a function of temperature and lipid as well as polycation/lipid composition. Several structural transitions are involved (i) the lipid chain melting (ii) the lamellar-isotropic transition of the membrane order, (iii) the columnar-smectic and smectic-isotropic transition of the positional DNA order and (iv) the helix-coil transition of the DNA as well as the interplay between the electrostatic protamine/DNA and cationic lipid/DNA interactions.