DOES THE DLVO ACCOUNT FOR INTERACTIONS BETWEEN CHARGED SPHERIC VESICLES

Zeta-Potentials for dioctadecyldimethylammonium chloride (DODAC) and sodium dihexadecylphosphate (DHP) vesicles as a function of NaCl concentration (C(e)) are obtained over an extensive range of salt concentration (10(-4)-10(-1) M) using particle microelectrophoresis. These estimates of the surface potential at a fixed vesicle size allow the calculation of theoretical stabilities for the vesicles (W) using a DLVO model adapted for interacting spheric vesicles without free parameters. The W values calculated are at least a factor 10(40) higher than the experimental stability ratios (W(e)) from vesicle flocculation under identical experimental conditions. The DLVO does not account for interactions between charged spherical vesicles.