title: Photocrosslinkable biodegradable responsive hydrogels as drug delivery systems.
abstract: Recently, controlled release from biocompatible materials has received much attention for biomedical applications. Due to their biocompatibility and biodegradability, glucopyranosides such as dextran appear as promising polymeric materials if one is able to regulate their rheological properties and the encapsulation/release efficiency. In this work graft polymer hydrogels from dextran and N-isopropylacrylamide (NIPAAm) were prepared and characterized. Dextran molecules were modified with 2-isocyanatoethylmethacrylate (IEMA) in order to obtain a polymer with carbon double bonds. Urethane linkages resulted from the reaction between hydroxyl groups (OH) of the dextran and isocyanate groups (NCO) of the IEMA. The obtained polymer was then crosslinked by UV irradiation in the presence of the photoinitiating agent Irgacure 2959 by CIBA. The drug Ondansetron was entrapped in the final system and its release profile was determined at 25 and 37°C. The characterization of the materials was accomplished by: ATR-FTIR (Attenuated Total Reflectance-Fourier Transform Infrared) spectroscopy, elemental analysis, lower critical solution temperature (LCST) determination, swelling behaviour evaluation, determination of surface energy by contact angle measurement and drug delivery profile studies.
authors.affiliation: Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima, Polo II, 3030-790 Coimbra, Portugal.
authors.forename: J F
authors.initials: JF
authors.lastname: Almeida
authors.forename: P
authors.initials: P
authors.lastname: Ferreira
authors.forename: A
authors.initials: A
authors.lastname: Lopes
authors.forename: M H
authors.initials: MH
authors.lastname: Gil
mesh_terms: D000932:Antiemetics / Q000378:metabolism / Q000627:therapeutic use; D001672:Biocompatible Materials / Q000737:chemistry* / Q000378:metabolism; D003911:Dextrans / Q000737:chemistry* / Q000378:metabolism; D004339:Drug Compounding / Q000379:methods*; D016503:Drug Delivery Systems / Q000379:methods*; D020100:Hydrogels / Q000737:chemistry* / Q000528:radiation effects; D017953:Isocyanates / Q000737:chemistry; D008689:Methacrylates / Q000737:chemistry; D009325:Nausea / Q000188:drug therapy; D017294:Ondansetron / Q000378:metabolism* / Q000627:therapeutic use; D017319:Photosensitizing Agents / Q000737:chemistry; D011407:Propane / Q000031:analogs & derivatives / Q000737:chemistry; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D014466:Ultraviolet Rays
chemical_list: C499598:2-hydroxy-1-(4-(hydroxyethoxy)phenyl)-2-methyl-1-propanone; D000932:Antiemetics; D001672:Biocompatible Materials; D003911:Dextrans; D020100:Hydrogels; D017953:Isocyanates; D008689:Methacrylates; D017319:Photosensitizing Agents; D012996:Solutions; D017294:Ondansetron; C029845:2-isocyanatoethyl methacrylate; D011407:Propane