Spontaneous Formation of Vesicles and Dispersed Cubic and Hexagonal Particles in Amino Acid-Based Catanionic Surfactant Systems

Abstract

Mixed catanionic surfactant systems based on amino acids were investigated with respect to the formation of liquid crystal dispersions and the stability of the dispersions. The surfactants used were arginine-N-lauroyl amide dihydrochloride (ALA) and N R -lauroyl-arginine-methyl ester hydrochloride (LAM), which are arginine-based cationic surfactants; sodium hydrogenated tallow glutamate (HS), a glutamic-based anionic surfactant; and the anionic surfactants sodium octyl sulfate (SOS) and sodium cetyl sulfate (SCS). It is demonstrated that in certain ranges of composition there is a spontaneous formation of vesicular, cubic, and hexagonal structures. The solutions were characterized with respect to internal structure and size by cryogenic transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS), and turbidity measurements. Vesicles formed spontaneously and were found for all systems studied; their size distribution is presented for the systems ALA/SCS/W and ALA/SOS/W; they are all markedly polydisperse. The aging process for the system ALA/SOS/W was monitored both by turbidity and by cryo-TEM imaging; the size distribution profile for the system becomes narrower and the number average radius decreases with time. The presence of dispersed particles with internal cubic structure (cubosomes) and internal hexagonal structure (hexosomes) was documented for the systems containing ALA and HS. The particles formed spontaneously and remained stably dispersed in solution; no stabilizer was required. (Cubosome and hexosome are USPTO registered trademarks of Camurus AB, Sweden.) The spontaneous formation of particles and their stability, together with favorable biological responses, suggests a number of applications.

The association of DNA and stable catanionic amino acid-based vesicles

“…This surfactant system was characterized elsewhere [34]. It was found that it, in analogy with several other mixed cationic-anionic surfactant systems, presents a spontaneous formation of vesicles having a long-term stability; in fact they remain over our extended times of investigation suggesting that they may be thermodynamically stable.…”

Investigation on the self-assembled behaviors of C18unsaturated fatty acids in arginine aqueous solution

“…21 Furthermore, ions of biological origin, such as choline and alkaline amino acids (lysine and arginine), have been used as counter-ions to disperse fatty acids because they exist in aqueous solution with different ionic states such as anionic, cationic and amphoteric, due to the amino groups and carboxyl groups. [22][23][24] The self-assembled structures formed by these two kinds of biomaterials can greatly increase the solubility of fatty acids in aqueous solution by decreasing the Kra point; 16,25 on the other hand, the ion of biological origin itself provides a benecial effect for biomedical applications.…”

Long-Living Intermediates during a Lamellar to a Diamond-Cubic Lipid Phase Transition: A Small-Angle X-Ray Scattering Investigation

“…2,[6][7][8]20 In particular, the phase transitions involving cubic mesophase formation by surfactants and lipids exhibit considerable complexity. [21][22][23][24][25][26][27][28][29][30][31][32][33] They have attracted growing interest 34 and have provoked investigations focusing on their analogy with the mesophase transitions in di-and triblock copolymers forming LC structures.…”