| Abstract
| - We demonstrate the unique ability of catanionic vesicles, formed by mixing single-tailed cationic and anionicsurfactants, to capture ionic solutes with remarkable efficiency. In an initial study (Wang, X.; Danoff, E. J.; Sinkov,N. A.; Lee, J.-H.; Raghavan, S. R.; English, D. S. Langmuir2006, 22, 6461) with vesicles formed from cetyltrimethylammonium tosylate (CTAT) and sodium dodecylbenzenesulfonate (SDBS), we showed that CTAT-rich(cationic) vesicles could capture the anionic solute carboxyfluorescein with high efficiency (22%) and that the solutewas retained by the vesicles for very long times (t1/2 = 84 days). Here we expand on these findings by investigatingthe interactions of both anionic and cationic solutes, including the chemotherapeutic agent doxorubicin, with bothCTAT-rich and SDBS-rich vesicles. The ability of these vesicles to capture and hold dyes is extremely efficient(>20%) when the excess charge of the vesicle bilayer is opposite that of the solute (i.e., for anionic solutes inCTAT-rich vesicles and for cationic solutes in SDBS-rich vesicles). This charge-dependent effect is strong enoughto enable the use of vesicles to selectively capture and separate an oppositely charged solute from a mixture of solutes.Our results suggest that catanionic surfactant vesicles could be useful for a variety of separation and drug deliveryapplications because of their unique properties and long-term stability.
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