title: An injectable biodegradable temperature-responsive gel with an adjustable persistence window.
abstract: ɛ-Caprolactone (CL) and 3-benzyloxymethyl-6-methyl-1,4-dioxane-2,5-dion (fLA), with a benzyloxymethyl group at the 3-position of the lactide, were randomly copolymerized. The methoxy polyethylene glycol (MPEG)-b-[poly(ɛ-caprolactone)-ran-poly(3-benzyloxymethyl lactide) (PCL-ran-PfLA)] diblock copolymers were designed such that the PfLA content (0-15 mol%) in the PCL segment was varied. The MPEG-b-(PCL-ran-PfLA) diblock copolymers were derivatized by introducing a pendant benzyl group (MC(x)L(y)-OBn), hydroxyl group (MC(x)L(y)-OH), or carboxylic acid group (MC(x)L(y)-COOH) at the PfLA segment. The derivatized MPEG-b-(PCL-ran-PfLA) diblock copolymer solutions exhibited sol-to-gel phase transitions upon a temperature increase. The sol-to-gel phase transition depended on both the type of functional pendant group on the PfLA and the PfLA content in the PCL segment. MC(x)L(y)-COOH diblock copolymer solutions formed gels immediately after injection into Fischer rats. The gels gradually degraded over a period of 0-6 weeks after the initial injection, and the rate of degradation increased for higher concentrations of PfLA. Immunohistochemical characterization showed that the in vivo MPEG-b-(PCL-ran-PfLA) diblock copolymer gels provoked only a modest inflammatory response. These results show that the MPEG-b-(PCL-ran-PfLA) diblock copolymer gel described here may serve as a minimally invasive therapeutic, in situ-forming gel system with an adjustable temperature-responsive and in vivo biodegradable window.
authors.affiliation: Department of Molecular Science and Technology, Ajou University, san 5, Suwon 443 749, Korea.
authors.forename: Jae Il
authors.initials: JI
authors.lastname: Kim
authors.forename: Da Yeon
authors.initials: DY
authors.lastname: Kim
authors.forename: Doo Yeon
authors.initials: DY
authors.lastname: Kwon
authors.forename: Hwi Ju
authors.initials: HJ
authors.lastname: Kang
authors.forename: Jae Ho
authors.initials: JH
authors.lastname: Kim
authors.forename: Byoung Hyun
authors.initials: BH
authors.lastname: Min
authors.forename: Moon Suk
authors.initials: MS
authors.lastname: Kim
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000138:chemical synthesis* / Q000737:chemistry; D001673:Biodegradation, Environmental; D002452:Cell Count; D002850:Chromatography, Gel; D003460:Crystallization; D004146:Dioxanes / Q000138:chemical synthesis / Q000737:chemistry; D005455:Fluorescent Antibody Technique; D005782:Gels / Q000138:chemical synthesis* / Q000737:chemistry; D020007:Implants, Experimental; D007267:Injections; D009682:Magnetic Resonance Spectroscopy; D008422:Materials Testing; D044367:Phase Transition; D011091:Polyesters / Q000138:chemical synthesis / Q000737:chemistry; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry; D051381:Rats; D011916:Rats, Inbred F344; D012996:Solutions; D013696:Temperature; D014783:Viscosity
chemical_list: D001672:Biocompatible Materials; D004146:Dioxanes; D005782:Gels; D011091:Polyesters; D012996:Solutions; C016240:polycaprolactone; D011092:Polyethylene Glycols; C028210:monomethoxypolyethylene glycol; C091880:dilactide