osteum and lauric-acid

The prediction of surfactant phase behavior has applications in a wide range of areas. An accurate modeling of liquid phase behavior can aid our understanding of colloidal process or be used to design phases that respond in a defined way to their environment. In this work, we use molecular dynamics to model the phase behavior of the ternary sodium laurate/sodium oleate/water system and compare the simulation results to experimental data. Simulations were performed with the GROMOS 53A6 united-atom force field and cover the entire ternary phase diagram, producing micellar, hexagonal, and lamellar phases. The aggregate simulation time for the 33 simulations performed during this study is 4.4 μs. We find that the simulations were able to model the experimentally observed liquid phase behavior accurately, showing that the carboxylate and lipid parameters of the 53A6 force field give very good quality results for the in silico prediction of liquid system phase behavior.

Topics: Ionic Liquids; Lauric Acids; Molecular Conformation; Molecular Dynamics Simulation; Oils; Oleic Acid; Water

In this report, we investigate the nanoparticle formation between random copolymers (RCPs) of methoxy-poly(ethylene glycol) monomethacrylate (MePEGMA) and (3-(methacryloylamino)propyl)trimethylammonium chloride (MAPTAC) and oppositely charged natural surfactants, sodium oleate and sodium laurate, using turbidimetric titration, steady-state fluorescence, dynamic light scattering, and electron microscopy. Though sodium oleate and sodium laurate are sparingly soluble in water, the nanoparticle complexes formed between the RCPs and these surfactants are soluble in the entire range of compositions studied here, including the stoichiometric electronetural complexes. The spherical nature of these nanoparticle complexes is revealed by electron microscopic (EM) analysis. Dynamic light scattering (DLS) showed that the average diameters of the nanoparticles are in the range 50 to 150 nm, which is supported by EM analysis. Pyrene fluorescence experiments suggested that these soluble nanoparticles have hydrophobic cores, which may solubilize hydrophobic drug molecules. The polarity index (I(1)/I(3)) obtained from the pyrene fluorescence spectra and the conductometric measurements showed that the critical concentration of fatty acid salts needed to obtain nanoparticles are in the order of 10(-4) M. Further, the complexation of such poorly water-soluble amphiphilic surfactants with polymers offers a useful method for the immobilization of hydrophobic compounds towards water-soluble drug carrier formulations. The formation of water-soluble nanoparticles by the self-assembly of fatty acid salts upon interacting with oppositely charged poly(ethylene glycol)-based polyions.

Topics: Bile Acids and Salts; Cations; Fluorescence; Lauric Acids; Molecular Probes; Nanostructures; Oleic Acid; Polyethylene Glycols; Sodium Dodecyl Sulfate

Four kinds of surfactants, sodium laurate, sodium myristate, sodium palmitate and sodium oleate were used to study the effects of surfactant coatings on the lifetime and attenuation of microbubbles. The changes in the size distribution of microbubbles prepared with these surfactants in saline were measured with a Coulter Multisizer (Coulter Electronics Ltd., Luton, UK). Frequency characteristics of ultrasonic attenuation of the microbubble suspensions were measured between 400 kHz and 6 MHz. From the changes in attenuation in the microbubble suspensions over time, it was found that the lifetime of microbubbles in a suspension also depends on the frequency of the irradiating ultrasound. The effect of surfactants on the frequency characteristics of attenuation was also studied, and characteristics of the surfactant coating, including shell elasticity and shell friction parameters were calculated from the measurement results. Microbubbles produced with sodium palmitate had the longest lifetime and the smallest average size. The shell had very little effect on the ultrasonic properties of microbubbles produced with sodium palmitate, suggesting that the sodium palmitate microbubbles behaved ultrasonically as free microbubbles.

Topics: Air; Carboxylic Acids; Coated Materials, Biocompatible; Contrast Media; Elasticity; Friction; Humans; Lauric Acids; Myristic Acid; Oleic Acid; Palmitic Acid; Particle Size; Polysaccharides; Surface-Active Agents; Time Factors; Ultrasonics; Ultrasonography

Solubilization rate and phase equilibrium studies were conducted for cholesterol in aqueous sodium oleate solutions. The components interacted to form a lamellar liquid crystalline phase, and this phenomenon was investigated as a potential method for cholesterol gallstone dissolution. Phase equilibria data for cholesterol-sodium oleate-water showed that the mesophase contained approximately equimolar amounts of cholesterol and oleate with large amounts of water. The cholesterol solubilization rate from a static pellet in sodium oleate solutions was much faster than dissolution in sodium cholate solutions and was independent of oleate concentration from 2.5 to 10%. In these experiments, the medium became a cloudy dispersion of liquid crystalline phase in the micellar solutions. The rate-limiting step in the solubilization process appears to be dispersion of fragments from the liquid crystalline layer on the cholesterol surface. This hypothesis was consistent with the kinetic effects of viscosity, stirring rate, and oleate concentration. By converting cholesterol to a liquid crystalline phase, the solubilization process avoids the limitations for micellar solubility and interfacial resistance which control cholesterol dissolution in bile salt-containing media.

Topics: Cholelithiasis; Cholesterol; Cholic Acids; Crystallization; Humans; Lauric Acids; Oleic Acid; Oleic Acids; Sodium Chloride; Solubility