title: Biophysical and structural properties of DNA.diC(14)-amidine complexes. Influence of the DNA/lipid ratio.
abstract: Cationic liposomes are used as vectors for gene delivery both in vitro and in vivo. Comprehension of both DNA/liposome interactions on a molecular level and a description of structural modifications involved, are prerequisites to an optimization of the transfection protocol and, thus, successful application in therapy. Formation and stability of a DNA/cationic liposome complex were investigated here at different DNA:lipid molar ratios (rho). Isothermal titration calorimetry (ITC) of cationic liposomes with plasmid DNA was used to characterize the DNA-lipid interaction. Two processes were shown to be involved in the complex formation. A fast exothermic process was attributed to the electrostatic binding of DNA to the liposome surface. A subsequent slower endothermic reaction is likely to be caused by the fusion of the two components and their rearrangement into a new structure. Fluorescence and differential scanning calorimetry confirmed this interpretation. A kinetic model analyzes the ITC profile in terms of DNA/cationic liposome interactions.
authors.affiliation: Laboratoire de Chimie Physique des Macromolécules aux Interfaces, Université Libre de Bruxelles, Campus Plaine CP 206/2, B-1050 Brussels, Belgium. vpector@ulb.ac.br
authors.forename: V
authors.initials: V
authors.lastname: Pector
authors.forename: J
authors.initials: J
authors.lastname: Backmann
authors.forename: D
authors.initials: D
authors.lastname: Maes
authors.forename: M
authors.initials: M
authors.lastname: Vandenbranden
authors.forename: J M
authors.initials: JM
authors.lastname: Ruysschaert
mesh_terms: D000578:Amidines; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism
chemical_list: D000578:Amidines; D008081:Liposomes; D004247:DNA