title: Physicochemical properties of PEG-grafted liposomes.
abstract: Egg phosphatidylcholine (EggPC) or dimyristoylphosphatidylcholine (DMPC) liposomes containing polyethylene glycol (PEG)-lipids covering a range of 0-30 mol% have been prepared by Extrusion method. The physicochemical properties including size evolution and calcein permeation were evaluated to investigate the effect of PEG-lipids on bilayer structure. The results from quasielasetic light scattering (QELS), freeze-fracture microscopy, and gel exclusion chromatography revealed that presence of low concentration of PEG-lipid results in decreasing of vesicle size and further increase in the PEG-lipid concentrations lead to a transition from the lamellar membranes to micelles. The permeability for calcein increased with increase in concentration of distearoylphosphatidylethanolamine (DSPE)-PEG. On the other hand, the permeability decreased with low amount of cholesterol-PEG (blow 20% cholesterol-PEG) and increased with high amount of it. The maximum concentration of PEG-lipid that may be incorporated without alteration of the liposome structure depends on the composition of the bilayer. The concentration of DSPE-PEG2000 incorporated into vesicles without damaging vesicle structures were <20 mol% for EggPC and <10% for DMPC.
authors.affiliation: Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Japan.
authors.forename: Supaporn
authors.initials: S
authors.lastname: Sriwongsitanont
authors.forename: Masaharu
authors.initials: M
authors.lastname: Ueno
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002784:Cholesterol / Q000737:chemistry; D002850:Chromatography, Gel; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D004337:Drug Carriers; D005452:Fluoresceins / Q000737:chemistry; D005614:Freeze Fracturing; D008081:Liposomes / Q000737:chemistry*; D008854:Microscopy, Electron; D010316:Particle Size; D010592:Pharmaceutic Aids; D010714:Phosphatidylethanolamines / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry*
chemical_list: D004337:Drug Carriers; D005452:Fluoresceins; D008081:Liposomes; D010592:Pharmaceutic Aids; D010714:Phosphatidylethanolamines; D010743:Phospholipids; C038089:1,2-distearoylphosphatidylethanolamine; D011092:Polyethylene Glycols; D002784:Cholesterol; D004134:Dimyristoylphosphatidylcholine; C007740:fluorexon