Conformational and segmental dynamics in lipid-based vesicles

We have performed a detailed analysis of the conformational and segmental dynamics in lipid-based vesicles using quasielastic neutron scattering. Our data evidence the presence of dynamical heterogeneities: the hydrogens in the headgroups and in the initial part of the hydrophobic chains perform slow diffusive motions in a confined volume; those belonging to the end part of the chains show a faster confined diffusivity together with torsional isomerization transitions. A model with three hydrogen populations has been proposed to describe the main features of this complex dynamics. The addition of a charged polysaccharide component to the vesicles mostly slows the dynamics of the headgroups and of the upper part of the acyl chains without significantly affecting the isomerization dynamics.