X-Ray Diffraction and NMR Studies on Mixtures of Non-Ionic Surfactant (C₁₂EO₂) and Phospholipids (POPC)

Abstract

We studied the temperature and concentration dependence of the POPC/C12EO2/water ternary system and identified and characterized the different phases occurring. The thermal behaviour is slightly dependent on the surfactant to lipid molar ratio R9 11 . At low surfactant content the behaviour is similar to the binary lipid/water system. Similarly at low lipid contents the system behaves similarly to the surfactant/water mixture. However, at molar ratios R311 between 2 and 3 a new hexagonal phase forms which is peculiar to the mixture. 2 H NMR measurements indicated the existence of a lamellar phase containing also curved surfaces additional to the flat ones. The surface area per surfactant molecule was calculated to 0.23 nm 2 which is in good agreement with the cross-section of a paraffinic chain.

Effects of oleic acid and its congeners, elaidic and stearic acids, on the structural properties of phosphatidylethanolamine membranes

“…C 12 EO 2 -POPC (1:2, mol/mol) mixtures are arranged into L ␤ and H II structures below 20ЊC, but only a single H II phase is observed above this temperature. Interestingly, in the two-phase region, the H II phase expands while heating, but when the system turns into a single H II phase, it undergoes contraction (35). A similar behavior was observed here for DEPE-OA, 10:1 (mol/mol).…”

MSI-78, an Analogue of the Magainin Antimicrobial Peptides, Disrupts Lipid Bilayer Structure via Positive Curvature Strain

“…or a surface area of 6800 Å 2 for a toroidal pore with b ¼ 20 Å and a ¼ 10 Å . If we assume that POPC has a crosssectional area of 65 Å 2 (Marsh, 1990;Funari et al, 1997), the surface area of a toroidal pore equals that of 105 lipids. Although it is not known how many peptides are required for the formation of a single pore, a reasonable estimate is five monomers per toroidal pore (Matsuzaki et al, 1998).…”

Mesoscopic simulation on phase behavior of star-like block polyether solution in the absence and presence of shear

“…Poly(ethylene oxide)-poly(propylene oxide) block copolymers are an important class of amphiphilic molecules, which exhibit a rich phase behavior as a function of solvent, temperature and pressure. [1][2][3][4][5][6][7][8][9] Many reports have been published on the aqueous solution properties and applications of this kind of copolymer, [10][11][12][13][14] and most of the published works deal with linear polymers such as Pluronic (BASF). [15][16][17][18] It is well known that the physicochemical properties and practical applications of amphiphilic molecules depend greatly upon their molecular structures.…”