Phase diagrams and the kinetics of phospholipid exchange for vesicles of different composition and radius

Interactions between dimyristoyl- and dipalmitoyl phosphatidylcholine vesicles have been studied by light scattering of dilute dispersions (concn less than or equal to 1 mg/ml). It was found that at 50 degrees C, the two types of vesicles exchange lipid molecules, irrespective of the initial radii of the pure vesicles. When the initial radii are different, the process leads eventually to vesicles of intermediate size. The reaction follows second order kinetics. At room temperature no reaction was observed. The phase diagrams for several lipid systems are discussed.