title: Sulfonamide-based pH- and temperature-sensitive biodegradable block copolymer hydrogels.
abstract: Novel pH- and temperature-sensitive biodegradable poly(epsilon-caprolactone-co-lactide)-poly(ethylene glycol) (PCLA-PEG) block copolymers were synthesized with oligomeric sulfamethazine (OSM) end groups (OSM-PCLA-PEG-PCLA-OSM). Aqueous solutions of these block copolymers have shown sol-gel transition behavior upon both temperature and pH changes under physiological conditions (37 degrees C, pH 7.4). The sol-gel transition of these block copolymer solutions was fine-tuned by controlling the PEG length, the hydrophobic to hydrophilic block ratio (PCLA/PEG), and the molecular weight of the sulfamethazine oligomer. Since changes in temperature do not induce gel formation in this pH- and temperature-sensitive block copolymer solution, this hydrogel can be employed as an injectable carrier using a long guide catheter into the body. In addition, the pH of the block copolymer solution showed no change following PCLA degradation over 1 month, and no indication of gel collapse was observed on addition of buffer solution. As such, these properties make the OSM-PCLA-PEG-PCLA-OSM hydrogel an ideal candidate for use as an injectable carrier for certain protein-based drugs known to denature in low-pH environments.
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: Sung Wan
authors.initials: SW
authors.lastname: Kim
authors.forename: Doo Sung
authors.initials: DS
authors.lastname: Lee
mesh_terms: D001673:Biodegradation, Environmental; D020100:Hydrogels / Q000138:chemical synthesis* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D008970:Molecular Weight; D044367:Phase Transition; D011091:Polyesters / Q000138:chemical synthesis* / Q000737:chemistry; D011092:Polyethylene Glycols / Q000138:chemical synthesis* / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D013449:Sulfonamides / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
chemical_list: D020100:Hydrogels; D011091:Polyesters; D012996:Solutions; D013449:Sulfonamides; C512884:poly(epsilon-caprolactone-co-lactide)-poly(ethylene glycol); D011092:Polyethylene Glycols