title: Gelation of charged catanionic vesicles prepared by a semispontaneous process.
abstract: Various stable charged catanionic vesicles with mean zeta-potential values from +59 mV to -96 mV were successfully prepared from an ion-pair amphiphile (dodecyltrimethylammonium-dodecylsulfate, DTMA-DS) and different amounts of the component ionic surfactants (dodecyltrimethylammonium bromide and sodium dodecyl sulfate) by using a simple semispontaneous process with the aid of cosolvent (1-propanol) addition in water. With the ensuring positively and negatively charged catanionic vesicles, gelation of them by four water-soluble polymers with various charge and hydrophobic characteristics was systematically studied by the tube inversion and rheological characteristic analyses. Four phase maps, which show regions of phase separation, viscous solution, and gel by varying the vesicle composition and polymer content, were thereby constructed. Furthermore, the experimental results of the relaxation time and the storage modulus at 1 Hz for the viscous solutions and gel samples revealed that the interactions at play between charged catanionic vesicles and the water-soluble polymers are of electrostatic and hydrophobic origin. The phase maps and the rheological properties obtained for mixtures of charged catanionic vesicles and polymers may provide useful information for the potential application of catanionic vesicles in mucosal or transdermal delivery of drugs.
authors.affiliation: Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan.
authors.forename: Zheng-Lin
authors.initials: ZL
authors.lastname: Huang
authors.forename: Jhen-Yi
authors.initials: JY
authors.lastname: Hong
authors.forename: Chien-Hsiang
authors.initials: CH
authors.lastname: Chang
authors.forename: Yu-Min
authors.initials: YM
authors.lastname: Yang