Characterization of a polymer-stabilized liposome system

Polymer-stabilized liposome systems and non-polymer-stabilized (conventiona l) liposome systems were investigated for particle size, lipid association, micropolarity, and migration of a fluorescent probe between lipid bilayers . The size difference between the two types of liposome systems prepared wi th identical procedure was determined using light scattering method. NMR sp ectroscopic analysis using deuterium-labeled lipids showed that under the s et conditions all lipids in both polymer-stabilized and conventional liposo me systems become associated. Environmental micropolarity assessment of pyr ene showed that the probe localizes within the lipid bilayers of both polym er-stabilized and conventional liposome systems. Further investigation reve aled that the bilayers of both systems were mobile enough to permit migrati on of the probe into neighboring unlabeled liposome bilayers. (C) 2001 Publ ished by Elsevier Science B.V.