Evidence for Multilamellar Vesicles in the Lamellar Phase of an Electrostatic Lyotropic Ternary System. A Solid State ²H-NMR and Freeze Fracture Electron Microscopy Study

Abstract

Deuterium solid state NMR and freeze fracture electron microscopy experiments have been carried out in the lamellar Lα phase of the water−sodium dodecyl sulfate−octanol system. Within the lamellar phase two types of bilayer organizations have been found. At high surfactant and alcohol concentrations, the lamellar phase is made of a stack of flat parallel bilayers while in the dilute part, it consists of multilayered vesicles of large radius (ca. 10 000 Å). These latter structures, commonly called spherulites, which appear spontaneously at low octanol contents and/or for high water dilution, can be described as textural defects of the lamellar phase. The location of this onion-like structure region is discussed within the framework of the membrane elasticity theory. As a side result, the presence of 33% glycerol in some of the freezefracture experiments is shown to barely affect the bending modulus of the film but rather disorder the molecular packing of the bilayers.

Shear-Induced Transitions between a Planar Lamellar Phase and Multilamellar Vesicles: Continuous versus Discontinuous Transformation

“…45 The residual couplings arise from the anisotropy of the rotational motions of the water molecules and thus depend on the curvature of the hydrophobic/hydrophilic interface. 24,43,44,46,47 When D 2 O molecules experience a macroscopically anisotropic environment, the quadrupolar interaction has a nonzero average, leading to a splitting of the resonance. In the case of uniaxial symmetry, as for the L R phase, the 2 H spectrum consists of a doublet with a frequency separation ∆ν given by 45,48 ∆ν )…”

Swollen and collapsed lyotropic lamellar rheology

“…This could be the situation of large polydispersed (giant) vesicles, especially vesicles with size >5 µm have been detected in the two-phase region of the phase diagram [17]. Auguste et al found a powder pattern characteristic to a spontaneously formed large MLV with radius of 10 µm for a diluted SDS/octanol system [26]. The thermodynamic stability of Lam 1 phase has been observed by following the spectra during 3 months.…”

Segmental order parameters in a nonionic surfactant lamellar phase studied with 1H–13C solid-state NMR

“…1 Over the last three decades, 2 H NMR has proven to be a very useful tool for this purpose. [2][3][4][5][6][7][8][9] The measurement of the 2 H quadrupolar couplings provides an insight into the order profiles of C-D bonds and can reveal information about molecular orientation and motion in lipid membranes as well as other liquid crystalline systems.…”