Span 80 vesicles have a more fluid, flexible and “wet” surface than phospholipid liposomes

► Span 80 vesicle has been shown to possess a flexible head group mobility and high membrane fluidity. ► Water molecules can invade the surface of the Span 80 vesicular membrane. ► Span 80 vesicle differs from liposome with regard to the mechanism of interaction between the membrane and cholesterol.