1,721,058 research outputs found
Quantification of Specific Anion Binding to Non-Ionic Triton X-100 Micelles
No full textAnion binding to nonionic micelles was quantified by self-diffusion. Four anions were probed by multinuclear PGSTE NMR measurements in a Triton X-100 micellar aqueous solution. The salt concentration used was sufficiently low to avoid any micellar growth affecting surface curvature. The micellar aggregates that provide a model surface are uncharged with hydrophilic headgroups so that electrostatic ion surface interactions play little or no role in prescribing specific anion binding. Anionic affinity to the micellar surface followed a Hofmeister series, (CH(3))(2)AsO(2)(-) >> CH(3)COO(-) > H(2)PO(4)(-) > F(-). The observed ion specificity is rationalized by calling into play the nonelectrostatic interactions occurring between the anions and the micellar surface
Monoolein Based Liquid Crystals to Form Long-Term Stable Emulsions
No full textIn recent investigations of multicomponent systems it has been observed that, as almost a general rule, very stable emulsions can be obtained whenever a hydrophobic or a hydrophilic 'solute' is dispersed in a liquid crystalline matrix. Some examples are presented. Long-term stable w/o emulsions were prepared by dispersing water in the lamellar and reverse hexagonal phases formed by monoolein-based systems. All these three-phase emulsions (water, reverse hexagonal and lamellar liquid crystals) resulted kinetically stable, provided that the water solute was added gradually to a previously formed liquid crystalline phase. (C) 2003 Elsevier B.V. All rights reserved
Liquid crystal based formulations for topical drug delivery
No full textMonoolein, being a biocompatible and bioadhesive penetration enhancer that can form liquid crystalline (LC) phases, possesses remarkable characteristics for addressing drug delivery systems across the biological membrane. A range of formulations based on LC phases were investigated in this study, which includes lamellar, reverse hexagonal, and bicontinuous cubic phases along with an emulsion stabilized by LC phases. Caffeine was chosen as hydophilic model drug to evaluate in vitro release performance. The different monoolein based caffeine formulations were characterized by techniques such as polarized light microscopy, nuclear magnetic resonance (NMR) and small angle x-ray scattering (SAXS). The release experiments, performed through Franz diffusion cells, revealed that the presence of a liquid crystalline (LC) phase prevented burst release in all cases. In addition, taking into consideration that all ingredients are fully biocompatible, the creamy emulsion formulation stabilized by a hexagonal lipid LC phase can be proposed as a challenging preformulation for topical drug delivery
Biocompatible lipidic formulations: phase diagrams and microstructure
No full textBiocompatible systems formulated for use in the food, cosmetic, and pharmaceutical fields are
characterized. Ternary phase diagrams of mixtures of natural lipids (glycerol trioleate, glycerol monooleate, diglycerol monooleate, and lecithin) and water were investigated by means of optical microscopy in polarized light and by multinuclear NMR spectroscopy. All systems showed a microemulsion region at high oil content and a large area of coexistence of two liquid crystalline (hexagonal and lamellar) phases. 1H and 13C NMR self-diffusion measurements were used to characterize microstructural features of the microemulsions. On water dilution, the two-phase liquid crystalline region transforms into a creamy
emulsion area where the droplets of water are stabilized by both the lamellar and the hexagonal phases, as indicated by 2H NMR measurements. Due to the very effective dispersing action of the two liquid
crystalline phases, these emulsions show a high stability toward phase separation
NMR investigation on Malaleuca alternifolia essential oil dispersed in the Monoolein aqueous system: phase behavior and dynamics
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