sodium-dodecyl-sulfate and tetradecyltrimethylammonium

The unique electrochemical properties of ionic liquids (ILs) have motivated their use as solvents for organic synthesis and green energy applications. More recently, their potential in pharmaceutical chemistry has prompted investigation into their effects on biomolecules. There is evidence that some ILs can destabilize proteins via a detergent-like manner; however, the mechanism still remains unknown. Our hypothesis is that if ILs are denaturing proteins via a detergent-like mechanism, detergent-mediated protein unfolding should be enhanced in the presence of ILs. The properties of myoglobin was examined in the presence of a zwitterionic (

Topics: Electrochemical Techniques; Ionic Liquids; Models, Molecular; Molecular Structure; Myoglobin; Organic Chemicals; Protein Unfolding; Sodium Dodecyl Sulfate; Thermodynamics; Trimethyl Ammonium Compounds

The usefulness of the micellar selectivity triangle (MST) for prediction and interpretation of separation patterns in micellar electrokinetic chromatography (MEKC) separations is presented. In addition, we demonstrate the capability of controlling selectivity properties of micelles through addition of organic modifiers with known solvation properties as predicted by MST. The examples are modification of the hydrogen bond donor (HBD) micelle of lithium perfluorooctanesulfonate, the hydrogen bond acceptor (HBA) micelle of tetradecyltrimethylammonium bromide, and the sodium dodecyl sulfate micelles with intermediate hydrogen bonding properties with two hydrophobic organic modifiers. One is an aliphatic alcohol, n-pentanol that can act as both a HBA and a HBD; by contrast, the other organic modifier is a fluorinated alcohol, hexafluoroisopropanol that is a strong HBD modifier and would enhance the hydrogen bond donor strength of micelles. A test sample composed of 20 small organic solutes representing HBA, HBD, and non-hydrogen bond aromatic compounds was carefully selected. The trends in retention behavior of these compounds in different micelles are consistent with the selectivity patterns predicted by the MST scheme. To the best of our knowledge, this is the first report on the unique selectivity of fluorinated alcohols as modifiers in MEKC. These results demonstrate the usefulness of the MST scheme for identifying pseudo-phases with highly similar or different selectivities and can serve as a guide for judicious selection of modifiers to create pseudo-phases with desired selectivity behavior on a rational basis.

Topics: Alcohols; Alkanesulfonic Acids; Chromatography, Micellar Electrokinetic Capillary; Fluorocarbons; Hydrogen Bonding; Hydrogen-Ion Concentration; Hydrophobic and Hydrophilic Interactions; Lithium; Micelles; Models, Chemical; Sodium Dodecyl Sulfate; Solvents; Trimethyl Ammonium Compounds

Three kinds of conventional surfactants, namely, two nonionic surfactants [polyethylene glycol (23) lauryl ether (Brij-35) and Triton X-100 (TX-100)], one cationic surfactant [n-tetradecyltrimethyl ammonium bromide (TTAB)], and an anionic surfactant [sodium n-dodecyl sulfate (SDS)}, were mixed into the quaternary ammonium gemini surfactant [C(14)H(29)N(+)(CH(3))(2)](2)(CH(2))(2).2Br(-) (14-2-14) in aqueous solution. The exchange rate constants between 14-2-14 molecules in the mixed micelles and those in the bulk solution were detected using two nuclear magnetic resonance (NMR) methods: one-dimensional (1D) line shape analysis and two-dimensional (2D) exchange spectroscopy (EXSY). The results obtained from these two methods were consistent. Both showed that mixing a nonionic conventional surfactant, either Brij-35 or TX-100, enhanced the exchange process between the 14-2-14 molecules in the mixed micelles and those in the bulk solution. In contrast, the anionic surfactant SDS and the cationic surfactant TTAB slowed the process slightly.

Topics: Cations; Magnetic Resonance Spectroscopy; Micelles; Octoxynol; Polyethylene Glycols; Quaternary Ammonium Compounds; Sodium Dodecyl Sulfate; Solutions; Surface-Active Agents; Thermodynamics; Trimethyl Ammonium Compounds

Gliclazide is practically insoluble in water, and has low dissolution rate. Therefore, it was of interest to improve its dissolution rate using anionic and cationic surfactants. The intrinsic dissolution rates of gliclazide in solutions of sodium dodecyl sulfate (SDS) and in solutions of tetradecyltrimethyl ammonium bromide (TDTMAB) were measured using the rotating disk method to study the convective diffusion transport of drug-loaded micelles. Two different approaches were applied to the experimental data; the convective diffusion model and the film equilibrium model. The two approaches are based on the same fundamental assumptions differing only in their interpretation of the diffusional boundary layer. The results obtained from the film equilibrium model were less satisfactory, and in case of TDTMAB the model was inapplicable (negative diffusion coefficient). While excellent results were obtained from the convective diffusion model. The free solute diffusion coefficient (D(s)) obtained experimentally was 2.47 x 10(-5) cm(2)/s, and the diffusion coefficient of the drug-loaded SDS micelle (D(sm)) estimated was 1.74 x 10(-6) cm(2)/s. The drug-loaded SDS micelle radius was 14 A. The thickness of the diffusional boundary layer was 54 and 22 microm for the free solute and the drug-loaded SDS micelle, respectively. TDTMAB showed lower effect in improving the dissolution rate of gliclazide than SDS. The drug-loaded TDTMAB micelle diffusion coefficient was 1.03 x 10(-6) cm(2)/s. The radius of the drug-loaded TDTMAB micelle and the boundary layer thickness were 24 A and 19 microm, respectively.

Topics: Diffusion; Gliclazide; Hypoglycemic Agents; Indicators and Reagents; Quaternary Ammonium Compounds; Sodium Dodecyl Sulfate; Solubility; Surface-Active Agents; Trimethyl Ammonium Compounds

The natural compound curcumin was incorporated into various micellar systems in order to improve the water solubility and the hydrolytic and photochemical stability. The presence of micellar structures resulted in an increase in water solubility at pH 5 by a factor of at least 10(5). The hydrolytic stability of curcumin under alkaline conditions was strongly improved by incorporation into micelles while the photodecomposition rate was increased compared to curcumin in hydrogen bonding organic solvents or aqueous solutions. The ability of curcumin to act as a photosensitizer was dependent on the type of micelles and pH of the medium.

Topics: Cetylpyridinium; Curcumin; Drug Stability; Hydrogen-Ion Concentration; Hydrolysis; Micelles; Octoxynol; Photochemistry; Quaternary Ammonium Compounds; Sodium Dodecyl Sulfate; Solubility; Solutions; Surface-Active Agents; Trimethyl Ammonium Compounds

The migration behavior and separation of six tetracyclines (TCs) were investigated by micellar electrokinetic chromatography (MEKC) in the pH range 5.0-9.0 using ammonium acetate buffer with the addition of sodium dodecyl sulfate (SDS). Mixed SDS-Brij 35, sodium cholate (SC) and tetradecyltrimethylammonium bromide (TTAB) were also used as surfactants. The influences of surfactant concentration and buffer pH on the separation of TCs were examined and the separations of TCs were optimized. Complete separation of six TCs was achieved within 8 min with 15 mM ammonium acetate buffer containing 20 mM SDS, with or without the addition of Brij 35 (0.135%, w/v), at pH 6.5 using a fused-silica capillary (42 cm x 75 microns I.D.) at 15 kV. In general, good linear correlations of the logarithm of migration factor (log k') versus the logarithm of octanol-water partition coefficient (log P(ow)) in these micellar systems, except for the TTAB-MEKC system, were obtained. The results indicate that the migration of TCs in MEKC is mainly based on hydrophobic interactions. However, hydrogen bonding interactions also play a significant role in influencing the chemical selectivity of TCs. In addition, the micelle-water partition coefficients (Pmw) of TCs, which are pH-dependent in the SDS-MEKC micellar system, are reported.

Topics: Anti-Bacterial Agents; Cholic Acid; Cholic Acids; Electrophoresis, Capillary; Hydrogen Bonding; Hydrogen-Ion Concentration; Micelles; Osmolar Concentration; Polidocanol; Polyethylene Glycols; Quaternary Ammonium Compounds; Sodium Dodecyl Sulfate; Surface-Active Agents; Tetracyclines; Trimethyl Ammonium Compounds

The oxidations of methyl linoleate micelles in aqueous dispersions induced by copper and iron have been studied, aiming specifically at elucidating the action of the copper ion in the chain initiation. Sodium dodecyl sulfate (SDS) and tetradecyltrimethylammonium bromide (TTAB) were used as anionic and cationic surfactants, respectively, in order to see the effect of the electric charge of the micelle surface. Both copper and iron induced the oxidations of methyl linoleate micelles by decomposing lipid hydroperoxide contained initially in methyl linoleate, tert-butyl hydroperoxide, or hydrogen peroxide added to the aqueous phase. The rate of oxidation induced by cupric ions was proportional to the first power of methyl linoleate concentration and to the half power of both cupric ion and hydroperoxide concentrations, suggesting that the oxidation was initiated by the peroxyl and alkoxyl radicals formed in the decomposition of hydroperoxide by copper. The formation of alkoxyl radicals was confirmed by its trapping with a spin trap. The rate of oxidation was dependent on the type of surfactant. Methyl linoleate containing a very small amount of hydroperoxide was oxidized by copper in the SDS system, but the rate of its oxidation was negligible when TTAB was used. However, the addition of tert-butyl hydroperoxide induced the oxidation even in the TTAB system. Hydroperoxyl and hydroxyl radicals formed in the SDS system induced the oxidation, but those formed in the TTAB system did not. It was shown that the effect of radicals on the initiation of lipid peroxidation depends on the type of radicals and site of radical formation.

Topics: Copper; Electricity; Free Radicals; Hydrogen Peroxide; Iron; Linoleic Acids; Lipid Peroxidation; Micelles; Oxidation-Reduction; Peroxides; Quaternary Ammonium Compounds; Sodium Dodecyl Sulfate; Spin Labels; Surface Properties; tert-Butylhydroperoxide; Trimethyl Ammonium Compounds; Vitamin E

Polyacrylamide gel electrophoresis in the presence of a cationic detergent, tetradecyltrimethylammonium bromide (TDAB) has been compared to electrophoresis in the presence of an anionic detergent, sodium dodecyl sulfate (SDS). Although, in both systems, the peptides generally migrated as a function of their molecular weight, the TDAB electrophoresis permitted us to obtain a much better resolution of several peptides of the mitochondrial F0-F1-ATPase, especially for the alpha and beta subunits and for the oligomycin sensitivity conferring protein (OSCP). The differences between the two electrophoretic profiles have been used to devise a new technique of two-dimensional electrophoresis using successively anionic and cationic detergents. This method could be very useful in the case of membrane proteins, which are generally soluble only in the presence of powerful ionic detergents. It has been particularly successful in resolving the small peptides of the F0-F1-ATPase which were difficult to differentiate by other techniques in one- or two-dimensional polyacrylamide gel electrophoresis.

Topics: Adenosine Triphosphatases; Animals; Carrier Proteins; Electrophoresis, Polyacrylamide Gel; Macromolecular Substances; Membrane Proteins; Mitochondria, Heart; Mitochondrial Proton-Translocating ATPases; Molecular Weight; Proton-Translocating ATPases; Quaternary Ammonium Compounds; Sodium Dodecyl Sulfate; Swine; Trimethyl Ammonium Compounds