Pluronic F-68 を用いた安定なリポソームの調製とその特性

抄録

Sterically stabilized liposomes were produced by incorporation a poly (oxyethylene) poly (oxypropylene) block copolymer (Pluronic F-68) into the lipid bilayer using a high-pressure homogenizer. Mean vesicle size of liposomes incorporating Pluronic F-68 greatly decreased from 480 nm to 110 nm with minor change in marker entrapment after passing three times through the high-pressure homogenizer. Liposomes stabilized with Pluronic F-68 were characterized with respect to entrapment efficiency, vesicle size and surface charge. Entrapment efficiency of a marker increased with Pluronic F-68 content, and was maximum at 0.13 (% wt/vol) -Pluronic F-68. In particle size and surface charge, no change was noted with increase in Pluronic F-68 content. Surface charge decreased slightly for liposomes incorporating Pluronic F-68, compared to those coated with Pluronic F-68. Pluronic F-68 is thus distributed between the bilayer and/ or inner phase of liposomes as well as the liposome surface. Liposomes stabilized with Pluronic F-68 were significantly stable in calcium and fetal bovine serum (FBS) solution at 37°C compared with Pluronic F-68-free liposomes. The incorporation of Pluronic F-68 into the bilayer caused significant increase in ³¹P-NMR line width. Pluronic F-68 is thus shown to stabilize liposomes by restricting phospholipid motion in the bilayer.