title: Synthesis and physical characterization of poly(ethylene glycol)-gelatin conjugates.
abstract: Poly(ethylene glycol) (PEG) with the terminal group of active ester was coupled to the amino group of gelatin to prepare PEG-grafted gelatin (PEG-gelatin). The affinity chromatographic study revealed that the PEG-gelatin with high degrees of PEGylation did not adsorb onto the gelatin affinity column, in remarked contrast to gelatin alone and the PEG-gelatin with low PEGylation degrees. The former PEG-gelatin showed a critical micelle concentration while it had the apparent molecular size of about 100 nm and a surface charge of almost zero. These findings indicate that the PEG-gelatin formed a micelle structure of which the surface is covered with PEG molecules grafted. When the body distribution of 125I-labeled gelatin and PEG-gelatin after intravenous injection was evaluated, the radioactivity of micellar PEG-gelatin was retained in the blood circulation compared with that of gelatin and the PEG-gelatin of no micelle formation. At the same PEGylation degree, the blood concentration was significantly higher for the PEG-gelatin prepared from PEG with a molecular weight of 12 000 than that of molecular weights of 2000 and 5000. It is concluded that the PEG-gelatin is a drug carrier with a micelle structure which retains in the blood circulation.
authors.affiliation: Department of Biomaterials, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawara-cho Shogoin, Sakyo-ku, Kyoto 606-8507, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Kushibiki
authors.forename: Hideki
authors.initials: H
authors.lastname: Matsuoka
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Tabata
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000493:pharmacokinetics*; D016503:Drug Delivery Systems; D005260:Female; D005780:Gelatin / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D051379:Mice; D008815:Mice, Inbred Strains; D008823:Micelles; D008970:Molecular Weight; D011092:Polyethylene Glycols / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D014018:Tissue Distribution
chemical_list: D001672:Biocompatible Materials; D008823:Micelles; D011092:Polyethylene Glycols; D005780:Gelatin