Vesicle catanionic

Marques, E. F., Regev, O., Khan, A., Miguel, M. D., and Lindman, B. (1998). Vesicle formation and general phase behavior in the catanionic mixture SDS-DDAB-water. The anionic-rich side. J. Phys. Chem. B, 102, 6746-58. 

Kepczynski M, Lewandowska J, Romek M et al. (2007) Silicone nanocapsules templated inside the membranes of catanionic vesicles. Langmuir 23 7314-7320. 

McKelvey, C.A., Kaler, E.W., Zasadzinski, J.A., Coldren, B. and Jung, H.T. (2000) Templating hollow polymeric spheres from catanionic equilibrium vesicles Synthesis and characterization. Langmuir, 16, 8285-8290. 

The kinetics of the decarboxylation of 6-NBlC has also been exantined in liposome dispersions and in spontaneously formed catanionic vesicles. For equimolar mixtures of n-cetyltrimethylanunonium bromide (CTAB) and sodium n-heptyl sulfate, k es (8.29 X 10 " s ) is higher than that in pure CTAB (k es = 6.76 x KF s ). Part of this rate increase may be due to the large concentration of NaBr in the solution. 

J. E. Kbjn, J. B. F. N. Engberts, Kemp elimination in membrane mimetic reaction media probing catalytic properties of catanionic vesicles formed from double-tailed amphiphiles, J. Am. Chem. Soc, 2003, 125, 1825-1833. 

The AC catanionic compound is thus actually much less ionic than its separated components. Experimental evidence indicates that such a surfactant mixture in water results in the formation of either a precipitate, a liquid crystal, or a vesicle structure, with a molecular arrangement that is likely to be of the bilayer type, which is no wonder, as the association compound obviously looks like a double-tailed surfactant [91-97]. 

Kepczynski, M. Lewandowska, J. Romek, M. Zapotoczny, S. Ganachaud, F. Nowakowska, M., Silicone Nanocapsules Templated Inside the Membranes of Catanionic Vesicles. Langmuir 2007, 23, 7314-7320. 

Kepczynski, M. Bednar, J. Lewandowska, J. Staszewska, M. Nowakowska, M., Hybrid Silica-Silicone Nanocapsules Obtained in Catanionic Vesicles. Cryo-TEM Studies. J. Nanosci. Nanotech. 2009, 9, 3138-3143. 

In some cases, vesicles can also be obtained simply by dissolving and mixing the required components in aqueous solution, that is, purely by self-assembly. For example, the so-called catanionic vesicles self-assemble when cationic and anionic amphiphiles (each in the form of a micellar solution) are mixed in an equimolar ratio. Also supramolecular amphiphiles (Section 3.3) form vesicles by self-assembly when two (or more) components are mixed in the appropriate molar ratio. 

Another strategy used vesicles constituted of catanionic surfactants resulting from the association of ionic surfactants of opposite charges. A triple-chained catanionic surfactant (TriCat) vras recently obtained via a spontaneaous acid-base reaction in water between AThexadecylamino-1-deoxylactitol and bis(hydro)g dodecyl)phosphinic acid, followed by pH measurements until stabilization (Fig. 16). A fluorescent double-chained catanionic amphiphile molecule (FluoCat) was also synthesized in order to label vesicles. In aqueous medium, TriCat-containing catanionic systems with or without the addition of FluoCat (TriCat and Tri-Cat/FluoCat 19/1) spontaneously self-assembled into stable vesicles, characterized by a narrow size distribution that did not exceed 200 nm in... 

Fig. 16 Chemical structures of TriCat and FluoCat used in catanionic vesicles.

Phase equilibria of systems containing oppositely charged ionic surfactants have been the subject of extensive experimental and theoretical investigations [39-61]. Competition between various molecular interactions (van der Waals, hydrophobic, electrostatic, hydration forces, etc.) may result in a variety of micro-structures, mixed micelles, vesicles, and catanionic surfactant salts. Mixing aqueous solutions of anionic surfactant with an equivalent amount of cationic surfactant (alkyl chains with more than eight atoms) results in precipitation of... 

A series of cationic gemini surfactants, alkanediyl-ot,a)-bis[di(2-hydro-xylethyl) dodecylammonium] dibromide (abbreviated as 12-S-12 (OH), with s = 4, 6, 8 and 10 methylenes) have been synthesized, and their aggregation properties in aqueous solution have been studied by surface tension, calorimetry, H NMR, DLS, and TEM. Two critical aggregation concentrations are observed for these surfactants. These surfactants start to form dimers at concentrations well below their critical micelle concentrations (CMC). Above the CMC, these surfactants can form both micelles and vesicles spontaneously with a micelle-to-vesicle transition.The formation and characterization of catanionic vesicles by newly synthesized lysine- and... 

Dialysis of surfactant mixtures of two oppositely charged surfactants (catanionic mixture) by combining HPLC, neutron activation, confocal microscopy, and NMR have been studied. In mixtures of n-alkyl tri-methylammonium halides and n-fatty acids, existence of a specific ratio between both surfactant contents (anionic/cationica 2 1) that determines the morphology, the elimination of ions, and the elimination of the solution cationic surfactant upon dialysis have been observed. In mixtures prepared with lower anionic surfactant contents, ill-defined aggregates are formed, and dialysis quickly eliminates the ion pairs (H-l-X) formed upon surfactant assocn. and also the cationic surfactant until a limiting 2 1 ratio is reached. By contrast, mixtures prepared above the anionic/cationic 2 1 ratio form micrometer-sized vesicles resistant to dialysis. ... 

It has been known for some time that the addition of some cationic surfactant to an anionic tends to increase the laundry performance [163-166], although the explanation is rather recent. In effect, the anionic and cationic surfactants react with each other to make a catanionic equimolar species that is much less hydrophilic but more surface active, particularly in relation to the wettability change. Such catanionic surfactants have been recently shown to produce microemuisions and vesicles (i.e., closed bilayer structures), so-called nanocapsules that may be considered as a water in water microemulsion. 

Wolf C, Bressel K, Drechsler M, Gradzielski M. Comparison of vesicle formation in zwitanionic and catanionic mixtures of hydrocarbon and fluorocarbon surfactants phase behavior and structural progression. Langmuir 2009 25 11358. 

A study on ionically-driven self-assembly of oligomeric aminosilicones, judiciously protonated with a variety of organic acids was carried out. Depending on the length of the silicone and the strength of the associated acids, (inverse) water-in-silicone emulsions, small nanoparticles, or catanionic vesicles were prepared and characterized by conventional (TEM) or original (DIG optical microscopy, DOSY NMR) techniques. For... 

Rosa, M., del Carmen Moran, M., da Graca Mignel, M. and Lindman, B. (2007) The association of DNA and stable catanionic amino acid-based vesicles. Colloids and Surfaces A Physicochem. Engng Aspects, 301, 361-375. 

S. Dey, D. K. Sasmal, D. K. Das, and K. Bhattacharyya, Chemphyschem, 9, 2848 (2008). A Femtosecond Study of Solvation Dynamics and Anisotropy Decay in a Catanionic Vesicle Excitation-Wavelength Dependence. 

Similarly to previous cases, a reversed series of cation binding is observed when sodium dodecyl sulfate micelles are replaced by sodium dodecanoate micelles. As measured by Haverd and Warr, the binding strength of alkali cations to the carboxylate micelles decreases in the order Na+ > K+ > Rb+ > Cs . The same order was observed also by electromotive force measurements. The same reversal in the counterion ordering was observed in catanionic systems with an excess of either SDS or sodium dodecanoate. These systems can form spontaneously vesicles with increasing concentration of added salt. 

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