Glucose encapsulation in catanionic vesicles and kinetic study of the entrapment/release processes in the sodium dodecyl benzene sulfonate/cetyltrimethylammonium tosylate/water system

The sodium dodecyl benzene sulfonate (SDBS)/cetyltrimethylammonium tosylate (CTAT)/water ternary system has previously been shown to give rise to the formation of vesicles for well-defined compositions requiring an excess of one of the surfactants over the other. Two types of vesicular systems can thus be obtained (named V+ and V-, depending on the nature of the excess surfactant, i.e., CTAT or SDBS, respectively). In addition, the pure ion-pair amphiphile (IPA) can be obtained after removing the counterions. These different systems (V+, V-, and IPA) were investigated in regards to their ability to susbtantially retain a hydrophilic probe such as glucose. The influence of the initial glucose and surfactant concentrations was studied, and dialysis experiments were conducted with a view to determine the kinetics of glucose entrapment and release by the vesicles and, thus, to assess the possibility of a long-term encapsulation. The results indicate that all the vesicular systems studied here are characterized by quite a high permeability of the amphiphilic bilayer. However, SDBS-rich (V-) and IPA vesicles proved to be less permeable than CTAT-rich (V+) vesicles. (C) 2002 Elsevier Science (USA).