Surfactant vesicles for high-efficiency capture and separation of charged organic solutes.
We demonstrate the unique ability of catanionic vesicles, formed by mixing single-tailed cationic and anionic surfactants, 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. Langmuir 2006, 22, 6461) with vesicles formed from cetyl trimethylammonium 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 solute was retained by the vesicles for very long times (t1/2 = 84 days). Here we expand on these findings by investigating the interactions of both anionic and cationic solutes, including the chemotherapeutic agent doxorubicin, with both CTAT-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 in CTAT-rich vesicles and for cationic solutes in SDBS-rich vesicles). This charge-dependent effect is strong enough to 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 delivery applications because of their unique properties and long-term stability.
Danoff
Emily J
EJ
Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742-2111, USA.
Wang
Xiang
X
Tung
Shih-Huang
SH
Sinkov
Nikolai A
NA
Kemme
Alice M
AM
Raghavan
Srinivasa R
SR
English
Douglas S
DS
D003116:Color; D015394:Molecular Structure; D009930:Organic Chemicals / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*; D013997:Time Factors
D009930:Organic Chemicals; D013501:Surface-Active Agents