Interaction of nucleic acids with lipid monolayer using X-ray diffraction techniques

Full text: Cationic lipids are of major interest as drug delivery systems of negatively charged drugs, proteins, biopolymers, genes, or the use of vaccines for prevention and treatment of infectious diseases. The insertion of a nucleic acid (DNA or RNA) in a target cell aiming at the production of a specific protein or the modification of metabolic pathways. Plasmid DNAs, different types of RNA (messenger, micro, silence) can be used, depending on the application. Liposomes composed of the ternary lipid composition of egg phosphatidylcholine (EPC), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) and 1,2-dioleeoyl-3-trimethylammonium-propane (DOTAP) have been successfully tested in vivo as DNA carriers against Hepatits B. Despite the promising in vivo results, there is a lack of information about of the ternary EPC/DOTAP/DOPE interaction with plasmid DNA, which could help to improve the formulations. In this work, we study a system formed by nucleic acids and Langmuir monolayer of EPC/DOTAP/DOPE using thermodynamic methods and X ray diffraction techniques. The X-ray diffraction techniques on Langmuir monolayers are convenient in this case, plays an important role in determining the properties of the molecular structure and packing of the membrane with the flexibility of in situ sample preparation varying subphase composition and surface pressure. (author)