Abstract
Vesicles are widely used in technological applications including cosmetic products, in microencapsulation for drug delivery, as anticancer agents and in the technology of adhesives, paints and inks. The vesicle size and the surface charge are very important properties from a technological point of view. Thus, the challenge in formulation is to find inexpensive stable vesicles with well-defined sizes and to modulate the surface charge of these aggregates. In this work we analyze the effect of different polymers on the structural properties of vesicles of the biodegradable surfactant sodium bis(2-ethyl-hexyl) sulfosuccinate, Aerosol OT. Using fluorescence, conductivity, electrophoretic mobility and dynamic light scattering measurements we study the effect of the polymer nature, molecular weight and polymer concentration on the stability and the vesicle size properties. Results demonstrate that it is possible to modulate both the size and the electric surface charge of spontaneous vesicles of Aerosol OT by the addition of very small percentages of poly(allylamine) and poly(maleic anhydride-alt-1-octadecen).
Highlights
Vesicles consist of a surfactant bilayer that separates an inner region of water from a continuous phase of the same fluid
The ζ-potential values for PA/Aerosol OT vesicles are almost independent of polymer concentration until the polymer concentration reaches a value of 0.005% w:w
The ζ-potential of vesicles sharply decreases indicating that the polycation PA partially neutralizes the surface negative charge of the Aerosol OT vesicles
Summary
Vesicles consist of a surfactant bilayer that separates an inner region of water from a continuous phase of the same fluid. To systematically investigate the effect of polymers on the vesicle properties, it is necessary to work with oppositely charged polymer and surfactant molecules and with a water insoluble polymer With this objective in mind we have selected the following polymers, poly(allylamine) (PA) and poly(maleic anhydride-alt-1-octadecen) (PMAO), Scheme 1. Langmuir monolayers [34] at the air-water interface; it is solubilized in the vesicle bilayer, thereby it offers the possibility of studying the effect of molecules incorporated into the membrane bilayer on the vesicle structure and properties To accomplish these objectives we obtain the cvc of mixed aggregates with different polymer composition by using electrical conductivity measurements. We use dynamic light scattering and electrophoretic mobility measurements to study the effect of the addition of PMAO and PA on the size of vesicles and on the electric properties of the vesicles surface, respectively
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