Preparation and characterization of Triclosan-containing vesicles

The vesicles containing various amount of Triclosan (TS) was prepared using N-[3-(dimethylamino)propyl]-octadecanamide (DMAPODA) and fatty acids as bilayer-forming materials. A multilayered and closed structure was observed on scanning electron microscopy (SEM). The vesicles free of TS exhibited a gel to liquid crystal transition temperature around 47 degreesC and the heat of transition was approximately 60 J/g. As the content of TS increased, the transition temperature and the enthalpy decreased probably due to the bilayer-fluidizing effect of TS. The absolute value of zeta potential of the vesicles decreased with increasing amount of TS. The surface charge density of the vesicles is likely to be reduced by TS intercalated into the vesicle bilayers. When pH was around 8.0, approximate point of zero charge of the vesicles, the vesicles aggregated probably due to the loss of electrostatic repulsion. By the addition of Ca2+, the turbidity of the vesicle suspensions remained stable at pH 6.0 where vesicles are positively charged but increased at pH 10 possibly due to the electrostatic interaction of Ca2+ and the negatively charged vesicles. The empty vesicle itself had stronger antimicrobial activity against Propionibacterium acnes than free TS. As a result, the vesicles containing TS had minimum inhibitory concentration (MIC) values lower than those of free TS. (C) 2002 Elsevier Science B.V. All rights reserved.