Kinetic pathway of spontaneous vesicle formation
Department of Physics and Astronomy, The University of Edinburgh
Mayfield Road, Edinburgh EH9 3JZ, UK
Corresponding author: S.U.Egelhaaf@ed.ac.uk
Accepted: 16 April 2002
The spontaneous formation of lipid vesicles (liposomes) in aqueous lecithin/bile salt mixtures is studied using time-resolved static and dynamic light scattering. These measurements reveal a strong dependence of the kinetic rates and end-state liposome properties on total amphiphile concentration and, even more pronounced, on ionic strength. The observed trends contradict equilibrium calculations, but are in quantitative agreement with a kinetic model that we present. This model identifies the key kinetic steps during vesicle formation: rapid formation of disc-like intermediate micelles, growth of these micelles and closure to form vesicles. This work offers conclusive evidence for kinetic rather than thermodynamic control of the end-state properties.
PACS: 82.70.Uv – Surfactants, micellar solutions, vesicles, lamellae, amphiphilic systems (hydrophilic and hydrophobic interactions) / 82.39.Rt – Reactions in complex biological systems / 87.14.Cc – Lipids
© EDP Sciences, 2002