Unilamellar vesicles obtained by simply mixing dioctadecyldimethylammonium chloride and bromide with water

Abstract: Optically clear dispersions of dioctadecyldimethylammonium bromide and chloride (DODAX, X=Br−, Cl−) in water can be obtained by simply mixing the amphiphiles at low concentrations (1mM) and at a temperature safely above the gel to liquid crystalline phase transition temperature (T m ≈45–48°C) of DODAX in water. Under these conditions, dynamic light scattering shows that, at room temperature, the dispersions contain two well-defined populations of large vesicles with average hydrodynamic radii (R H) of 80 and 337nm for DODAB and of 69 and 247nm for DODAC. Cryo-transmission electron microscopy (cryo-TEM) micrographs show that DODAX vesicles are unilamellar and polydisperse with apparent radius up to 800nm. The vesicles are stable for at least 1 month according to the ageing time-dependence of the turbidity and molar absorption coefficient. [Copyright &y& Elsevier]