Spontaneous Vesicle Formation in Catanionic Mixtures of Amino Acid-Based Surfactants: Chain Length Symmetry Effects.

Eduardo Marques, Rodrigo de Oliveira Brito, Sandra Silva, J Rodríguez-Borges, Maria Vale, Paula Gomes, Maria Araújo, Olle Söderman

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55 Citations (SciVal)


The use of amino acids for the synthesis of novel surfactants with vesicle-forming properties potentially enhances the biocompatibility levels needed for a viable alternative to conventional lipid vesicles. In this work, the formation and characterization of catanionic vesicles by newly synthesized lysine- and serine-derived surfactants have been investigated by means of phase behavior mapping and PFG-NMR diffusometry and cryo-TEM methods. The lysine-derived surfactants are double-chained anionic molecules bearing a pseudogemini configuration, whereas the serine-derived amphiphile is cationic and single-chained. Vesicles form in the cationic-rich side for narrow mixing ratios of the two amphiphiles. Two pairs of systems were studied: one symmetric with equal chain lengths, 2C 12/C 12, and the other highly asymmetric with 2C 8/C 16 chains, where the serine-based surfactant has the longest chain. Different mechanisms of the vesicle-to-micelle transition were found, depending on symmetry: the 2C 12/C 12 system entails limited micellar growth and intermediate phase separation, whereas the 2C 8/C 16 system shows a continuous transition involving large wormlike micelles. The results are interpreted on the basis of currently available models for the micelle-vesicle transitions and the stabilization of catanionic vesicles (energy of curvature vs mixing entropy).
Original languageEnglish
Pages (from-to)11009-11017
Issue number19
Publication statusPublished - 2008

Subject classification (UKÄ)

  • Physical Chemistry


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