Stability and swelling behaviour of a concentrated sponge phase

Gomati, R.; Bouguerra, Nizar; Gharbi, A.

doi:10.1016/s0921-4526(00)00770-5

Cited by 9 publications

(5 citation statements)

References 14 publications

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“…The SAXS diffraction curve of the dispersed CBZ-loaded system exhibited a wide peak (Figure B), which is typical of a sponge phase, , in support of the cryo-TEM findings.…”

Section: Resultssupporting

confidence: 80%

Solubilization of Hydrophobic Guest Molecules in the Monoolein Discontinuous Q_L Cubic Mesophase and Its Soft Nanoparticles

et al. 2008

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Hydrophobic bioactive guest molecules were solubilized in the discontinuous cubic mesophase (QL) of monoolein. Their effects on the mesophase structure and thermal behavior, and on the formation of soft nanoparticles upon dispersion of the bulk mesophase were studied. Four additives were analyzed. They were classified into two types based on their presumed location within the lipid bilayer and their influence on the phase behavior and structure. Differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), polarized light microscopy, cryogenic-transmission electron microscopy (cryo-TEM), and dynamic light scattering (DLS) were used for the analysis. We found that carbamazepine and cholesterol (type I molecules) likely localize in the hydrophobic domains, but close to the hydrophobic-hydrophilic region. They induce strong perturbation to the mesophase packing by influencing both the order of the lipid acyl chains and interactions between lipid headgroups. This results in significant reduction of the phase transition enthalpy, and phase separation into lamellar and cubic mesophases above the maximum loading capacity. The inclusion of type I molecules in the mesophase also prevents the formation of soft nanoparticles with long-range internal order upon dispersion. In their presence, only vesicles or sponge-like nanoparticles form. Phytosterols and coenzyme Q10 (type II molecules) present only moderate effects. These molecules reside in the hydrophobic domains, where they cannot alter the lipid curvature or transform the QL mesophase into another phase. Therefore, above maximum loading, excess solubilizate precipitates in crystal forms. Moreover, when type II-loaded QL is dispersed, nanoparticles with long-range order and cubic symmetry (i.e., cubosomes) do form. A model for the growth of the ordered nanoparticles was developed from a series of intermediate structures identified by cryo-TEM. It proposes the development of the internal structure by fusion events between bilayer segments.

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“…The SAXS diffraction curve of the dispersed CBZ-loaded system exhibited a wide peak (Figure B), which is typical of a sponge phase, , in support of the cryo-TEM findings.…”

Section: Resultssupporting

confidence: 80%

Solubilization of Hydrophobic Guest Molecules in the Monoolein Discontinuous Q_L Cubic Mesophase and Its Soft Nanoparticles

et al. 2008

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“…For example, at [GC11BS] = 40 wt%, d did not increase as the temperature was raised, indicating that all the available solvent had been absorbed by the lamellar phase at 25 °C. Whereas the increase in d spacing with decreasing gelator concentration and increasing temperature is consistent with swelling of a lamellar L α phase, this combination eliminates the possibility of a bicontinuous lamellar L 3 “sponge” phase, which would be insensitive to temperature 4 (A) The dependence of the interlayer spacing, d , as measured by SAXS, on temperature and GC11BS weight fraction in mixtures of GC11BS and p -xylene.…”

Section: Resultsmentioning

confidence: 81%

Lyotropic Phases Reinforced by Hydrogen Bonding

Martin

Ward

2005

Langmuir

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Amphiphilic guanidinium alkylbenzenesulfonates (GCnBS; n = number of carbons in the alkyl chain) exhibited lyotropic behavior in aqueous and organic solvents. The GCnBS compounds formed gel-like phases in certain cyclic organic solvents (e.g. p-xylene, cyclohexane) through the formation of swollen interdigitated lamellar phases reinforced by hydrogen bonding between the guanidinium ions and sulfonate moieties. This behavior was not observed for the homologous sodium alkylbenzenesulfonates, indicating that hydrogen bonding, mediated by the guanidinium (G) ion, was required for gel formation. Infrared spectroscopy unambiguously demonstrated the existence of the quasi-hexagonal hydrogen-bonded sheet typically adopted by G ions and the sulfonate groups in layered, solvent-free crystalline phases of the compounds, supporting lamellar structures in the gels. Small-angle X-ray scattering analysis of these gels revealed GCnBS lamellar phases with interlayer spacings (d) that increased with increasing temperature, consistent with increased absorption of solvent by the nonpolar regions of the gelator. At the lower gelator concentrations, the increase in d-spacing achieved at the higher temperatures exceeded the sum of the alkylbenzene chain lengths, suggesting either long-range interactions between the GS sheets or undulation stabilized lamellae, which have been reported in aqueous lamellar gels. The GCnBS compounds also formed lyotropic phases in water, but the phase behavior was more complex than that of the organogels. The rheology suggested gel-like behavior associated with entangled worm-like micelles at these higher concentrations. These lyotropic phases were reminiscent of crystalline layered and tubular architectures exhibited by various guanidinium organomonosulfonate compounds. These lyotropic phases expand the liquid crystal behavior observed for GS compounds beyond recently observed thermotropic smectic phases, adding to the portfolio of phase behavior exhibited by these materials.

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“…This value is within the range characteristic for other sponge phases. 38,39 The lattice parameters of a sponge phase made with jeffamine were reported recently. 31 Finally, when the upper phase was stored at 4°C for a week, it was transformed to a birefringent lamellar phase.…”

Section: Resultsmentioning

confidence: 99%

Lipidic Sponge Phase Crystallization of Membrane Proteins

Wadsten

Wöhri

Snijder

et al. 2006

Journal of Molecular Biology

100

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Stability and swelling behaviour of a concentrated sponge phase

Cited by 9 publications

References 14 publications

Solubilization of Hydrophobic Guest Molecules in the Monoolein Discontinuous Q_L Cubic Mesophase and Its Soft Nanoparticles

Solubilization of Hydrophobic Guest Molecules in the Monoolein Discontinuous Q_L Cubic Mesophase and Its Soft Nanoparticles

Lyotropic Phases Reinforced by Hydrogen Bonding

Lipidic Sponge Phase Crystallization of Membrane Proteins

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Stability and swelling behaviour of a concentrated sponge phase

Cited by 9 publications

References 14 publications

Solubilization of Hydrophobic Guest Molecules in the Monoolein Discontinuous QL Cubic Mesophase and Its Soft Nanoparticles

Solubilization of Hydrophobic Guest Molecules in the Monoolein Discontinuous QL Cubic Mesophase and Its Soft Nanoparticles

Lyotropic Phases Reinforced by Hydrogen Bonding

Lipidic Sponge Phase Crystallization of Membrane Proteins

Contact Info

Product

Resources

About

Solubilization of Hydrophobic Guest Molecules in the Monoolein Discontinuous Q_L Cubic Mesophase and Its Soft Nanoparticles

Solubilization of Hydrophobic Guest Molecules in the Monoolein Discontinuous Q_L Cubic Mesophase and Its Soft Nanoparticles