IN-VITRO RELEASE CHARACTERISTICS OF BIOACTIVE MOLECULES FROM DEXTRAN DIALDEHYDE CROSS-LINKED GELATIN HYDROGEL FILMS

Hydrogel films, prepared by cross-linking of gelatin with dextran dial dehydes (weight ratio 2:1), and containing either fluorescein isothioc yanate-dextran (M-w 70 000) or polypeptides were evaluated in terms of their release characteristics and mechanical properties upon increasi ng storage time at 4 degrees C. Important changes in release kinetics and mechanical properties of the cross-linked gelatin films were obser ved, especially during the first week after the hydrogel production. R heological and NMR measurements showed that the mechanical properties of the gelatin hydrogel films were improved with increasing storage ti me. It appeared that the process of chemical cross-linking and physica l structuring of the gelatin hydrogel matrix did not occur instantaneo usly and substantially influenced the polypeptide release patterns. Cr oss-linked gelatin hydrogels were found to be appropriate release syst ems for medium-term sustained delivery of biologically active epiderma l growth factor (EGF), but release characteristics were strongly depen dent on the nature of the protein which was incorporated. (C) 1998 Pub lished by Elsevier Science Ltd. All rights reserved.