Abstract
We applied a time-resolved small-angle neutron scattering (SANS) technique to the vesicle system of phospholipids to determine the lipid dynamics. This technique takes advantage of the large difference in the scattering length density between hydrogenated and deuterated lipids, and the exchange of these lipids between vesicles results in a decrease in the scattering intensity, which can be detected by time-resolved SANS measurements. Vesicles consisting of deuterated (D-LUV) or hydrogenated phospholipid (H-LUV) with a diameter of ca. 100nm were prepared using Tris-buffered saline of D2O/H2O mixture that has a mean scattering length density between D-LUV and H-LUV. The SANS intensity from the mixtures of D-LUV and H-LUV was reduced over time, and the observed kinetics could be explicitly represented by a simple model that includes two independent kinetic parameters, i. e., the rates of transbilayer and interbilayer exchange. In addition, these dynamics were found to depend strongly on acyl chain length of the lipids and the presence of cholesterol.
