title: Langmuir monolayer properties of the fluorinated-hydrogenated hybrid amphiphiles with dipalmitoylphosphatidylcholine (DPPC).
abstract: Surface pressure-area (pi-A), surface potential-area (DeltaV-A), and dipole moment-area (mu( perpendicular)-A) isotherms were obtained for the Langmuir monolayer of two fluorinated-hydrogenated hybrid amphiphiles (sodium phenyl 1-[(4-perfluorohexyl)-phenyl]-1-hexylphosphate (F6PH5PPhNa) and (sodium phenyl 1-[(4-perfluorooctyl)-phenyl]-1-hexylphosphate (F8PH5PPhNa)), DPPC and their two-component systems at the air/water interface. Monolayers spread on 0.02 M Tris buffer solution (pH 7.4) with 0.13M NaCl at 298.2K were investigated by the Wilhelmy method, ionizing electrode method and fluorescence microscopy. Moreover, the miscibility of two components was examined by plotting the variation of the molecular area and the surface potential as a function of the molar fraction for the fluorinated-hydrogenated hybrid amphiphiles on the basis of the additivity rule. The miscibility of the monolayers was also examined by construction of two-dimensional phase diagrams. Furthermore, assuming the regular surface mixture, the Joos equation for analysis of the collapse pressure of two-component monolayers allowed calculation of the interaction parameter (xi) and the interaction energy (-Deltaepsilon) between the fluorinated-hydrogenated hybrid amphiphiles and DPPC. The observations by a fluorescence microscopy also supported our interpretation as for the miscibility in the monolayer state. Comparing the monolayer behavior between the two binary systems, no remarkable difference was found among various aspects. Among the two combinations, the mole fraction dependence in monolayer properties was commonly classified into two ranges: 0 <or= X <or= 0.3 and 0.3 < X <or = 1. Dependence of the chain length of fluorinated part was reflected for the molecular packing and surface potential.
authors.affiliation: Division of Biointerfacial Science, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Fukuoka 812-8582, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Hoda
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Nakahara
authors.forename: Shohei
authors.initials: S
authors.lastname: Nakamura
authors.forename: Shigemi
authors.initials: S
authors.lastname: Nagadome
authors.forename: Gohsuke
authors.initials: G
authors.lastname: Sugihara
authors.forename: Norio
authors.initials: N
authors.lastname: Yoshino
authors.forename: Osamu
authors.initials: O
authors.lastname: Shibata
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D000388:Air; D004566:Electrodes; D005466:Fluorocarbons / Q000737:chemistry*; D006865:Hydrogenation; D008567:Membranes, Artificial; D008856:Microscopy, Fluorescence; D015394:Molecular Structure; D010755:Organophosphates / Q000737:chemistry*; D010316:Particle Size; D011312:Pressure; D012680:Sensitivity and Specificity; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D005466:Fluorocarbons; D008567:Membranes, Artificial; D010755:Organophosphates; D013501:Surface-Active Agents; C510767:phenyl 1-((4-perfluorohexyl)phenyl)-1-hexylphosphate; C510768:phenyl 1-((4-perfluorooctyl)phenyl)-1-hexylphosphate; D014867:Water; D015060:1,2-Dipalmitoylphosphatidylcholine