title: Interfacial Properties of Binary Systems Composed of DPPC and Perfluorinated Double Long-Chain Salts with Divalent Counterions of Separate Electric Charge.
abstract: The interfacial behavior of binary monolayers of 1,1'-(1,ω-alkanediyl)-bispyridinium perfluorotetradecanecarboxylate (CnBP(FC14)2, n = 2, 6, or 10) and dipalmitoylphosphatidylcholine (DPPC) was studied using surface pressure (π)-area (A) and surface potential (ΔV)-A isotherm measurements and morphological observations. In a previous study, we showed that the spacer moieties of C2BP(FC14)2and C6BP(FC14)2are completely dissociated after spreading on 0.15 M NaCl, whereas the C10BP(FC14)2spacer moieties do not dissociate in the monolayer state. However, in the present study, the ΔV-A isotherm indicated that the C10BP moiety partially dissociates in the presence of DPPC monolayers. The excess Gibbs free energy of mixing and two-dimensional phase diagrams suggest that CnBP(FC14)2is miscible with DPPC monolayers and also has a fluidizing effect on DPPC monolayers. The phase behavior of the binary monolayers was observed with Brewster angle microscopy (BAM), fluorescence microscopy (FM), and atomic force microscopy (AFM). The dispersion mode of DPPC-rich domains by C10BP(FC14)2is significantly different from those of the other CnBP(FC14)2monolayers. These results suggest that the aliphatic chains in phospholipids control the dissociation of divalent spacers bound to fluorinated surfactants or amphiphiles.
authors.affiliation: Department of Biophysical Chemistry, Graduate School & Faculty of Pharmaceutical Sciences, Nagasaki International University.
authors.forename: Riku
authors.initials: R
authors.lastname: Kato
authors.affiliation: Department of Biophysical Chemistry, Graduate School & Faculty of Pharmaceutical Sciences, Nagasaki International University.
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Nakahara
authors.affiliation: Department of Biophysical Chemistry, Graduate School & Faculty of Pharmaceutical Sciences, Nagasaki International University.
authors.forename: Osamu
authors.initials: O
authors.lastname: Shibata
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine; D005466:Fluorocarbons; D054879:Halogenation; D006838:Hydrocarbons; D018625:Microscopy, Atomic Force; D008856:Microscopy, Fluorescence; D044367:Phase Transition; D010743:Phospholipids; D012965:Sodium Chloride; D055672:Static Electricity; D013499:Surface Properties; D013501:Surface-Active Agents
chemical_list: D005466:Fluorocarbons; D006838:Hydrocarbons; D010743:Phospholipids; D013501:Surface-Active Agents; D015060:1,2-Dipalmitoylphosphatidylcholine; D012965:Sodium Chloride
keywords: AFM; BAM; DPPC; FM; fluorinated amphiphiles; surface potential; surface pressure