title: Dynamic interaction between oppositely charged vesicles: aggregation, lipid mixing, and disaggregation.
abstract: We investigated dynamic interactions between oppositely charged small unilamellar vesicles using positively charged vesicles containing 1,2-dioleoyl-3-trimethylammonium-propane or 3beta-[N-(N('),N(')-dimethylaminoethane)-carbamoyl] cholesterol and negatively charged vesicles containing L-alpha-phosphatidyl-DL-glycerol. Aggregation, lipid bilayer mixing, contents mixing and contents leakage were systematically examined using optical density measurements, fluorescence resonance energy transfer assays, fluorescence quenching assays, light-scattering analyses, and freeze-fracture transmission electron microscopy. The oppositely charged vesicles aggregated immediately. Lipid mixing was observed, but there was no mixing of the contents. The vesicle aggregates disaggregated spontaneously after several minutes. The surface potential of the disaggregated vesicles was neutralized. From these results, we infer that the lipids in the external monolayers were exchanged between the oppositely charged vesicles while the internal monolayers remained intact. The two types of cationic lipids used exhibited different speeds of disaggregation.
authors.affiliation: Research Center of Advanced Bionics (RCAB), National Institute of Advanced Industrial Science and Technology (AIST), Central 5th, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Saeki
authors.forename: Shinji
authors.initials: S
authors.lastname: Sugiura
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Baba
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Kanamori
authors.forename: Seigo
authors.initials: S
authors.lastname: Sato
authors.forename: Sukekuni
authors.initials: S
authors.lastname: Mukataka
authors.forename: Sosaku
authors.initials: S
authors.lastname: Ichikawa
mesh_terms: D031541:Fluorescence Resonance Energy Transfer; D008027:Light; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes; D012542:Scattering, Radiation
chemical_list: D008051:Lipid Bilayers; D008081:Liposomes