Vesicle-Surfactant Interactions:Effects of Added Surfactants on the Gel to Liquid-crystal Transition for Two Vesicular Systems

Interactions of both cationic and anionic surfactants with vesicles formed by dimethyldioctadecylammonium bromide (DOAB) and by sodium didodecylphosphate (DDP) have been probed using differential scanning microcalorimetry. The scans show that the surfactants are incorporated into the vesicle bilayers. The change in the melting temperature, Tm, characterising the gel to liquid-crystal transition depends on whether the charges on the head groups of surfactant ion and vesicular ion have either similar or opposite signs