Phase Behavior and Aggregate Structure in Aqueous Mixtures of Sodium Cholate and Glycerol Monooleate

Gústafsson, Jónas; Nylander, Tommy; Almgren, Mats; Ljusberg‐Wahren, Helena

doi:10.1006/jcis.1998.5996

Cited by 104 publications

(100 citation statements)

References 34 publications

(44 reference statements)

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“…Their morphology has similarities with other micellar systems that have been identified and reported previously (50). As documented earlier (32), after 30 min (40% of hydrolysis) only micelles and material originated from the pancreatic lipase could be detected (Fig.…”

Section: Visualization Of Structures Generated During In Vitro Lipolysupporting

confidence: 51%

Colloidal Structures in Media Simulating Intestinal Fed State Conditions with and Without Lipolysis Products

et al. 2008

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Section: Visualization Of Structures Generated During In Vitro Lipolysupporting

confidence: 51%

Colloidal Structures in Media Simulating Intestinal Fed State Conditions with and Without Lipolysis Products

et al. 2008

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“…59,60 Toward mimicking the physiological conditions for protein drug delivery, the research is being extended to fully hydrated cubic lipid systems for protein nanoconfinement. 11,14,50,56,[64][65][66][67][68][69][70] …”

Section: Biomolecular Uptake and Release Governed By The Hydration Lementioning

confidence: 99%

Self-Assembled Multicompartment Liquid Crystalline Lipid Carriers for Protein, Peptide, and Nucleic Acid Drug Delivery

et al. 2010

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L ipids and lipopolymers self-assembled into biocompatible nanoand mesostructured functional materials offer many potential applications in medicine and diagnostics. In this Account, we demonstrate how high-resolution structural investigations of bicontinuous cubic templates made from lyotropic thermosensitive liquid-crystalline (LC) materials have initiated the development of innovative lipidopolymeric self-assembled nanocarriers. Such structures have tunable nanochannel sizes, morphologies, and hierarchical inner organizations and provide potential vehicles for the predictable loading and release of therapeutic proteins, peptides, or nucleic acids. This Account shows that structural studies of swelling of bicontinuous cubic lipid/water phases are essential for overcoming the nanoscale constraints for encapsulation of large therapeutic molecules in multicompartment lipid carriers.For the systems described here, we have employed time-resolved small-angle X-ray scattering (SAXS) and high-resolution freeze-fracture electronic microscopy (FF-EM) to study the morphology and the dynamic topological transitions of these nanostructured multicomponent amphiphilic assemblies. Quasi-elastic light scattering and circular dichroism spectroscopy can provide additional information at the nanoscale about the behavior of lipid/protein self-assemblies under conditions that approximate physiological hydration.We wanted to generalize these findings to control the stability and the hydration of the water nanochannels in liquidcrystalline lipid nanovehicles and confine therapeutic biomolecules within these structures. Therefore we analyzed the influence of amphiphilic and soluble additives (e.g. poly(ethylene glycol)monooleate (MO-PEG), octyl glucoside (OG), proteins) on the nanochannels' size in a diamond (D)-type bicontinuous cubic phase of the lipid glycerol monooleate (MO). At body temperature, we can stabilize long-living swollen states, corresponding to a diamond cubic phase with large water channels. Time-resolved X-ray diffraction (XRD) scans allowed us to detect metastable intermediate and coexisting structures and monitor the temperature-induced phase sequences of mixed systems containing glycerol monooleate, a soluble protein macromolecule, and an interfacial curvature modulating agent. These observed states correspond to the stages of the growth of the nanofluidic channel network.With the application of a thermal stimulus, the system becomes progressively more ordered into a double-diamond cubic lattice formed by a bicontinuous lipid membrane. High-resolution freeze-fracture electronic microscopy indicates that nanodomains are induced by the inclusion of proteins into nanopockets of the supramolecular cubosomic assemblies. These results contribute to the understanding of the structure and dynamics of functionalized self-assembled lipid nanosystems during stimuli-triggered LC phase transformations.

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“…Moreover, direct imaging seems especially informative, as demonstrated by Strey and Jalm[3], who used the freeze fracture electron microscopy (FFEM) to visualize bicontinuous structures in a three-component microemulsion. Since then, FFEM and Cryo-TEM have been widely used to study the microstructure of microemulsions [4][5][6][7][8][9].In the present work, we studied the effect of octane on the phase behavior of CTAB/water/I-butanol system and found the largest one-phase microemulsion region (Winsor N). The phase diagram CTAB/I-butanol In-octane/water has been mapped for the fixed (surfactant + alcohol)/oil weight ratio 90/10.…”

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confidence: 99%

mentioning

confidence: 99%

A study of the microstructure of CTAB/1-butanol/octane/ water system by PGSE-NMR and Cryo-TEM

Zhai

et al. 2001

Chin. Sci. Bull.

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In this work, the effect of octane concentration on the phase behavior of CTAB/water/l-butanol system was studied by using pulsed field gradient spin-echo NMR measurements and freeze fracture electron microscopy (Cryo-TEM and FFEM). When the octane concentration increases, the liquid crystalline phase is destabilized and a continuous single-phase microemulsion region from the water apex to the oil apex is formed. The conductivity behavior has a distinct percolative phenomenon, which indicates that the single-phase microemulsion is changed continuously from oilin-water (o/w) structure via a bicontinuous structure to water-in-oil (w/o) structure. This result is consistent with those of the PGSE-NMR, Cryo-TEM, and FFEM. In the w/o region, the self-diffusion coefficient of water is relatively high «1---6) X 10-l0 m • S-l) due to the higher solubility of water in the continuous phase consisting of octane (10% by weight) and I-butanol. The penetration of a large amount of octane molecules between surfactant chains results in the much lower self-diffusion coefficient of octane.Microemulsions are transparent, isotropic, thermodynamically stable dispersions of oil and water, stabilized by surfactant molecules [l]. Four-component systems of surfactant, cosurfactant (generally a short chain linear alcohol), oil, and water have many important features and are the most intensively studied microemulsion systems. The reason for the significance of these systems is that the introduction of cosurfactant greatly extends the isotropic solution region, especially with single chain ionic surfactants. One of the most basic aspects of any surfactant system, besides thermodynamic stability, is its microstructure. Microemulsions based on cationic surfactant cetyltrimethylammonium bromide (CTAB) have been extensively used as hosts for enzymes and microreactor for polymerization and preparation of nanosize particles. Despite such widespread interest in CTAB microemulsion, the structure of a quaternary microemulsion is not easy to verify, which can be seen from the fact that several studies, 1272 despite the use of a wide range of experimental techniques, have made only a little progress in getting a reliable picture of these systems. A useful characterization of microemulsions is via the identification of whether the oil and water domains are closed (to form "droplets") or not; hence a classification into oil-in-water (o/w) droplets, w/o droplets, and "bicontinuous" structures [2]. A well-established method for detecting changes of the microstructure of microemulsions is the measurement of self-diffusion coefficients by NMR techniques. On the time scale of NMR experiments one is concerned with molecular self-diffusion over macroscopic distances of the order of micrometers (i.e. distances much larger than the size of microemulsion droplets). Therefore, the experiment is not sensitive to molecular displacements within the droplets. Accordingly, in the case of an o/w microemulsion the monitored translation of the oil molecules in the droplet ...

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Phase Behavior and Aggregate Structure in Aqueous Mixtures of Sodium Cholate and Glycerol Monooleate

Cited by 104 publications

References 34 publications

Colloidal Structures in Media Simulating Intestinal Fed State Conditions with and Without Lipolysis Products

Colloidal Structures in Media Simulating Intestinal Fed State Conditions with and Without Lipolysis Products

Self-Assembled Multicompartment Liquid Crystalline Lipid Carriers for Protein, Peptide, and Nucleic Acid Drug Delivery

A study of the microstructure of CTAB/1-butanol/octane/ water system by PGSE-NMR and Cryo-TEM

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