title: Aggregation of dipalmitoylphosphatidylcholine vesicles.
abstract: Quasi-elastic and 90 degrees light scattering were used to study the aggregation of dipalmitoylphosphatidylcholine vesicles at temperatures below the gel-liquid-crystalline phase transition as a function of concentration, temperature, and size. Increased vesicle concentration did not appreciably change aggregate size but did change the total number of aggregates in a manner consistent with a bimolecular collisional mechanism for the conversion of aggregates to fused vesicles. Increased temperature decreased aggregation, indicating that the disaggregation rate constant increased faster than the aggregation rate constant. As a function of size, aggregation decreased slightly from small to 700 A diameter vesicles and increased considerably for 950 A diameter vesicles. A model of the interaction of small vesicles below the gel-liquid-crystalline phase transition is presented in which aggregation precedes fusion and collision between aggregates triggers fusion.
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003080:Cold Temperature; D007700:Kinetics; D008027:Light; D008081:Liposomes; D011663:Pulmonary Surfactants; D012542:Scattering, Radiation
chemical_list: D008081:Liposomes; D011663:Pulmonary Surfactants