title: Effect of poly(ethylene glycol) grafts on temperature-sensitivity of thermosensitive polymer-modified liposomes.
abstract: A copolymer of N-isopropylacrylamide and N-acryloylpyrrolidine, which exhibits a lower critical solution temperature (LCST) at 38 degrees C, having a didodecyl group at the chain terminal was synthesized and calcein-loaded liposomes were prepared from a mixture of dioleoylphosphatidylethanolamine and the copolymer. While the contents release from the copolymer-modified liposomes was strongly accelerated around the LCST of the copolymer, some extent of the release was also observed below the LCST, probably because the partly-dehydrated copolymer chains interacted with the liposome membrane. When poly(ethylene glycol) with the number average molecular weight of 550 having a didodecyl group at the chain end was introduced into the copolymer-modified liposomes, the contents release from the copolymer-modified liposomes was effectively suppressed below the LCST but hardly affected above the LCST. As a result, the liposomes exhibited much sharper enhancement of the contents release in a narrow temperature region. The temperature-sensitive contents release property of the copolymer-modified liposomes became less significant in the presence of serum. However, inclusion of the anchor-bearing poly(ethylene glycol) derivative improved the contents release behavior of the copolymer-modified liposomes in the presence of serum.
authors.affiliation: Department of Applied Materials Science, Graduate School of Engineering, Osaka Prefecture University 1-1, Gakuen-cho, Sakai, Osaka 599-8531, Japan. kono@ams.osaka-u.ac.jp
authors.forename: Kenji
authors.initials: K
authors.lastname: Kono
authors.forename: Keisuke
authors.initials: K
authors.lastname: Yoshino
authors.forename: Toru
authors.initials: T
authors.lastname: Takagishi
mesh_terms: D002626:Chemistry, Pharmaceutical; D006358:Hot Temperature; D008081:Liposomes / Q000737:chemistry* / Q000493:pharmacokinetics; D011092:Polyethylene Glycols / Q000737:chemistry* / Q000493:pharmacokinetics; D011108:Polymers / Q000737:chemistry* / Q000493:pharmacokinetics; D013696:Temperature
chemical_list: D008081:Liposomes; D011108:Polymers; D011092:Polyethylene Glycols