Spontaneously Formed Vesicles From Various Surfactant Mixtures And Studies Of Their Properties

In the dissertation, the spontaneously formed vesicles and their properties were characterized in detail.Vesicles were formed spontaneously in aqueous solution of SDBS/LSB,AOT/ TX-100 and SDBS/TX-100 just under the inducement of salt. The existence of vesicles was demonstrated by TEM image using negative-staining method. The vesicle regions were presented in three pseudo-ternary diagrams of SDBS/LSB/Brine, AOT/TX-100/ Brine and SDBS/TX-100/Brine respectively. The variations of vesicle size with the salinity and mixing ratios, as well as the surfactant concentration were determined using dynamic light scattering method.The inducement of salt makes the determination of critical vesicle concentration possible. We have employed fluorescence method to monitor the inner micro-enviromental change during the aggregate structural transition, accompanied by a turbidity and conductivity measurement to follow the outer change of the aggregate structures. Pyrene was used as a fluorescence probe. The ratio of the fluorescence intensity of Pyrene I1/I3 precisely reflects the inner microenvironment change.Finally, the encapsulation and releasing of fluorescence dye Calcein by spontaneously formed vesicle, from the mixtures of SDBS/LSB/brine, AOT/LSB/brine and SDBS/CTAB was studied with a simple but sensitive and accurate fluorescence method, using cobalt chloride as a quenching agent. The two compounds are commercially available and there is no separation of vesicle from bulk media. The entrapment quantity of vesicles to the Calcein, inversely proportional to the permeability, was successfully deduced according to the difference of fluorescence intensity before and after the quenching.