HYDROGELS PREPARED BY CROSS-LINKING OF GELATIN WITH DEXTRAN DIALDEHYDE

Hydrogels were prepared by reaction of gelatin with partial periodate oxidized dextran. It was found that the rate of gelation depends on th e molecular weight and on the degree of oxidation of dextran, the type of gelatin and on the reaction conditions. Rheological measurements d emonstrate that the gel strength is governed by two factors: chemical crosslinking by reaction with polyaldehyde and physical structuring of the gelatin. By proper selection of the reaction conditions, in parti cular storage temperature, the contribution of both processes to the f inal material strength can be varied. It was observed that short cryog enic treatment significantly enhances the chemical crosslinking.