title: Implantable controlled delivery systems for proteins based on collagen--pHEMA hydrogels.
abstract: Co-polymeric hydrogels of collagen and poly(hydroxyethyl methacrylate) (pHEMA) were prepared using an ammonium persulphate-sodium metabisulphite redox initiation technique. Fluorescein isothiocyanate (FITC)-labelled bovine serum albumin (BSA) was entrapped into these hydrogels. These gels were modified differently by external cross-linking and made highly porous by incorporation of ethylene glycol. The morphological characteristics of the gels containing FITC-BSA before and after release were studied. The in vitro release of FITC-labelled BSA was studied in phosphate buffer, pH 7.4, at 37 degrees C. The results clearly indicated that collagen-pHEMA hydrogels release FITC-BSA in a zero-order fashion. In the case of uncross-linked hydrogels, the release of FITC-BSA was about 81% within 8 d, compared to 49% for the same period in the case of cross-linked hydrogels. It was also observed that in the case of porous hydrogels the release was very fast (19% in the first hour) and lasted for about 12 h, releasing 76% of FITC-BSA. These results clearly indicated that collagen-pHEMA hydrogels released BSA in a zero-order fashion and that the release rate can be programmed by appropriate modification of the hydrogel matrices.
authors.affiliation: Biomaterials Laboratory, Central Leather Research Institute, Adyar, Madras, India.
authors.forename: J K
authors.initials: JK
authors.lastname: Rao
authors.forename: D V
authors.initials: DV
authors.lastname: Ramesh
authors.forename: K P
authors.initials: KP
authors.lastname: Rao
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D002417:Cattle; D003094:Collagen / Q000648:ultrastructure; D003432:Cross-Linking Reagents; D004343:Drug Implants; D016650:Fluorescein-5-isothiocyanate / Q000008:administration & dosage / Q000031:analogs & derivatives; D005782:Gels; D066298:In Vitro Techniques; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction; D011102:Polyhydroxyethyl Methacrylate; D012710:Serum Albumin, Bovine / Q000008:administration & dosage
chemical_list: D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D004343:Drug Implants; D005782:Gels; C039217:fluorescein isothiocyanate bovine serum albumin; D011102:Polyhydroxyethyl Methacrylate; D012710:Serum Albumin, Bovine; D003094:Collagen; D016650:Fluorescein-5-isothiocyanate