Cationic Dihexadecyldimethylammonium Bromide Research Articles

Solution Properties of Mono- and Di-hexadecyl Cationic Mixed Surfactant Systems: Specific Coexistence Effect Among Various Aggregates

We have synthesized the surfactant cationic dihexadecyl dimethyl ammonium bromide [16-16]. The aggregates of [16-16] and hexadecyl trimethyl ammonium bromide (C16TAB) were prepared in aqueous solution in different mixing ratio (x[16-16]) of [16-16]. The effect of mixing ratio (x[16-16]) and experimental temperature on the aggregates formation were studied using a number of physicochemical methods. With an increase in x[16-16], the structure of aggregates changed from spherical micelles to vesicles. In the range of specific ratio (0.2 ≤ x[16-16] ≤ 0.4) and temperature (35 and 45 ºC), worm-like micelles existed. We have demonstrated that x[16-16] and temperature played an important role in deciding the type of aggregate formed in solution.

Polymer Migration among Phospholipid Liposomes

Complexation of phospholipid lipsomes with a cationic polymer, poly(N-ethyl-4-vinylpyridinium bromide) (PEVP), and subsequent interliposomal migration of the adsorbed macromolecules, have been investigated. Liposomes of two different charge types were examined: (a) a liposomal system, with an overall charge near zero, consisting of zwitterionic phosphatidylcholine (egg lecithin, EL) with added doubly anionic phospholipid, cardiolipin (CL(2-)), and cationic dihexadecyldimethylammonium bromide (HMAB(+)), in a CL(2-)/HMAB(+) charge-to-charge ratio of 1:1; (b) an anionic liposomal system composed of an EL/CL(2-) mixture plus polyoxyethylene monocetyl ether (Brij 58). Both three-component systems were designed specifically to preclude liposomal aggregation upon electrostatic association with the PEVP, a phenomenon that had complicated analysis of data from several two-component liposomes. PEVP macromolecules were found from fluorescence experiments to migrate among the charge-neutral EL/CL(2-)/HMAB(+) liposomes. In the case of anionic EL/CL(2-)/Brij liposomes, a combination of fluorescence and laser microelectrophoresis methods showed that PEVP macromolecules travel from liposome to liposome while being electrostatically associated with anionic lipids.