title: Span 80 vesicles have a more fluid, flexible and "wet" surface than phospholipid liposomes.
abstract: The surface properties of Span 80 vesicles at various cholesterol contents, together with those of various liposomes, were characterized by using fluorescence probes. The membrane fluidity of the Span 80 vesicles was measured by 1,6-diphenyl-1.3.5-hexatriene (DPH) and trimethlyammonium-DPH (TMA-DPH), and the results suggested that the surface of the Span 80 vesicles was fluid due to the lateral diffusion of Span 80 molecules. The depolarization measured by TMA-DPH and the headgroup mobility measured by dielectric dispersion analysis indicated the high mobility of the head group of Span 80 vesicles. This suggested that the surface of Span 80 vesicles was flexible due to the head group structure of Span 80, sorbitol. In addition, spectrophotometric analysis with 6-dodecanoyl-N, N-dimethyl-2-naphthylamine and 8-anilino-1-naphthalenesulfonic acid indicated that the water molecules could easily invade into the interior of the Span 80 vesicle membrane, suggesting that the membrane surface was more wet than the liposome surface. These surface properties indicated that the protein could interact with the interior of vesicle membranes, which was similar to the case of cholesterol. Thus the present results confirmed that the Span 80 vesicle surfaces showed the unique characteristics of fluidity, flexibility, and "wetness", whereas the liposome surfaces did not.
authors.affiliation: Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Hayashi
authors.forename: Toshinori
authors.initials: T
authors.lastname: Shimanouchi
authors.forename: Keiichi
authors.initials: K
authors.lastname: Kato
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Miyazaki
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nakamura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Umakoshi
mesh_terms: D015081:2-Naphthylamine / Q000031:analogs & derivatives / Q000737:chemistry; D000817:Anilino Naphthalenesulfonates / Q000737:chemistry; D002784:Cholesterol / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D004560:Electricity; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes / Q000737:chemistry; D006601:Hexoses / Q000737:chemistry*; D007848:Laurates / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D008560:Membrane Fluidity; D009113:Muramidase / Q000378:metabolism; D010743:Phospholipids / Q000737:chemistry*; D018583:Pliability; D012997:Solvents; D013050:Spectrometry, Fluorescence; D017155:Wettability
chemical_list: C515594:8-anilino-1-naphthalenesulfonic acid; D000817:Anilino Naphthalenesulfonates; D005456:Fluorescent Dyes; D006601:Hexoses; D007848:Laurates; D008081:Liposomes; D010743:Phospholipids; D012997:Solvents; C018665:sorbitan monooleate; D002784:Cholesterol; D015081:2-Naphthylamine; D009113:Muramidase; C065580:laurdan