Spontaneous vesicle formation in catanionic mixtures of amino acid-based surfactants: Chain length symmetry effects

• Type: Article in International Scientific Journal
• Date: 2008

Authors

Eduardo F Marques (Author) FCUP; Rodrigo O Brito (Author) Other; Sandra G Silva (Author) Other; Enrique E Rodriguez Borges (Author) FCUP; Maria Luisa do Vale (Author) FCUP; Paula Gomes (Author) FCUP; Maria J Araujo (Author) FCUP; Olle Soderman (Author) Other

Journal

Title: Langmuir

Vol. 24 No. 16

Pages: 11009-11017

ISSN: 0743-7463

Publisher: American Chemical Society

Indexing

ISI Web of Knowledge - 54 Citations

Scopus - 59 Citations

Scientific classification

FOS: Engineering and technology > Materials engineering

Other information

Authenticus ID: P-003-VJF

DOI: 10.1021/la801518h

Abstract (EN): 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 2C12/C12 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).

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 9