title: Effects of poly(ethylene glycol) (PEG) concentration on the permeability of PEG-grafted liposomes.
abstract: Poly(ethylene glycol)-grafted liposomes (PEG-liposomes) were prepared from dipalmitoylphosphatidylcholine (DPPC) with various amounts of distearoyl-N-monomethoxy poly(ethylene glycol)-succinyl-phosphatidylethanolamines (DSPE-PEG) with PEG molecular weights of 1000, 2000, 3000 and 5000. The effects of DSPE-PEG concentration on the permeability of PEG-liposomes were investigated using carboxyfluorescein (CF). In the gel state, the CF leakage from PEG-liposomes was decreased with increasing mole fractions of DSPE-PEG for all PEG molecular weights. In the liquid-crystalline state, the CF leakage from PEG-liposomes containing DSPE-PEG1000 gradually increased with increasing mole fractions of DSPE-PEG, while that of PEG-liposomes whose molecular weight in PEG units was above 2000 rapidly decreased by the addition of DSPE-PEG. Furthermore, no effect of PEG molecular weight on CF leakage was observed. The relationship between the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) (or 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH)) and the mole fraction of DSPE-PEG for PEG-liposomes was also investigated. No significant changes in fluorescence polarization of DPH for liposomal bilayer membranes was observed in the gel and liquid-crystalline states due to the addition of DSPE-PEG, while that of TMA-DPH was decreased compared with that of liposomes without DSPE-PEG in both states.
authors.affiliation: College of Pharmacy, Nihon University, Chiba, Japan. khashiza@pha.nihon-u.ac.jp
authors.forename: Kaname
authors.initials: K
authors.lastname: Hashizaki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Taguchi
authors.forename: Chika
authors.initials: C
authors.lastname: Itoh
authors.forename: Hideki
authors.initials: H
authors.lastname: Sakai
authors.forename: Masahiko
authors.initials: M
authors.lastname: Abe
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Saito
authors.forename: Naotake
authors.initials: N
authors.lastname: Ogawa
mesh_terms: D004305:Dose-Response Relationship, Drug; D008081:Liposomes / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D010539:Permeability / Q000187:drug effects; D011092:Polyethylene Glycols / Q000008:administration & dosage* / Q000493:pharmacokinetics*
chemical_list: D008081:Liposomes; D011092:Polyethylene Glycols