title: Novel injectable pH and temperature sensitive block copolymer hydrogel.
abstract: A novel pH and temperature sensitive block copolymer was prepared by adding pH sensitive moiety to temperature sensitive block copolymer. This block copolymer solution showed a reversible sol-gel transition by a small pH change in the range of pH 7.4-8.0 and also by the temperature change in the region of body temperature. The very precise molecular weight control of block copolymer and the prudential tuning of hydrophilic-hydrophobic balance were needed to control the phase diagram. This block copolymer solution forms a gel at 37 degrees C, pH 7.4 (human body). When the block copolymer solution is at room temperature and pH 8.0 as a sol state, both the temperature and pH change are needed for the gelation. This material can be employed as injectable carriers for hydrophobic drugs and proteins, etc. Gelation inside the needle can be prevented by an increase in the temperature during injection, because it does not change into the gel form with only increasing temperature. This material can be used for even a long guide catheter into the body. The block copolymer hydrogel which shows the sol-gel transition by the small pH change from pH 8.0 to pH 7.4 has merits in the delivery system for protein and cells which show cytotoxicity in acidic (below pH 6.5) or basic (above pH 8.5) conditions. This block copolymer system could be used as a template technology for injectable delivery systems.
authors.affiliation: Department of Polymer Science & Engineering, Sungkyunkwan University, Suwon, Gyunggi 440-746, Korea.
authors.forename: Woo Sun
authors.initials: WS
authors.lastname: Shim
authors.forename: Jae Sun
authors.initials: JS
authors.lastname: Yoo
authors.forename: You Han
authors.initials: YH
authors.lastname: Bae
authors.forename: Doo Sung
authors.initials: DS
authors.lastname: Lee
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D001831:Body Temperature; D004337:Drug Carriers; D016503:Drug Delivery Systems; D005782:Gels / Q000737:chemistry*; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry; D020100:Hydrogels; D006863:Hydrogen-Ion Concentration; D007267:Injections; D046911:Macromolecular Substances / Q000737:chemistry*; D008956:Models, Chemical; D008970:Molecular Weight; D044367:Phase Transition; D011092:Polyethylene Glycols / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D013696:Temperature; D014783:Viscosity
chemical_list: D001672:Biocompatible Materials; D004337:Drug Carriers; D005782:Gels; D020100:Hydrogels; D046911:Macromolecular Substances; D011108:Polymers; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D011092:Polyethylene Glycols