Dielectric Behavior of an Aqueous System of Multi-wall Vesicles Formed with 1,2 dioleoyl-sn-glycero-3[phospho-L-serine] sodium salt

Abstract

Dielectric behavior was examined for an aqueous solution of a two-tail lipid, 1,2 dioleoyl-sn-glycero-3[phospho-L-serine] sodium salt (DOPS Na). At the concentration and temperatures examined (0.02 g cm−3 and 15-60 °C), the lipid molecules formed unilamellar and multilamellar vesicles having a large, correlated fluctuation in curvature. The system exhibited the dielectric dispersion attributable to the electrode polarization of the mobile ion, Na+. The observed dispersion frequency and intensity were higher and smaller, respectively, than those expected for the Na+ ions freely moving between the electrodes. This result suggested that the motion of Na+ in the DOPS-Na system was mostly confined between the vesicle walls. Furthermore, analysis of the dielectric behavior of the DOPS Na system at various T suggested that the spatial confinement for the Na+ motion loosens with increasing T.