Synthesis and properties of hyaluronic acid containing copolymers crosslinked by γ-ray irradiation

Biocompatible and biodegradable hydrogels based on polyvinylpyrrolidone (PVP), gelatin and hyaluronic acid (HA were prepared using a gamma irradiation polymerization technique, and their characteristics were examined. The degree of gelation for these systems was between 55-85% and increased with increasing gelatin or PVP content increased. The gel fraction of the HA/gelatin hydrogel was 30% larger than that of the HA/PVP hydrogel when exposed to a 30-50 kGy radiation dose. The increase in cross-linking density by gamma irradiation was confirmed by TGA. Swelling studies of the hydrogels prepared under various conditions were carried out in aqueous solutions ranging in pH from 2-8 to determine the pH sensitivity. The hydrogels based on HA had the highest swollen water content with a ratio of 1:10 (HA:gelatin and 1:5 (HA:PVP and a 30 kGy radiation dose. HA/gelatin gels showed a large swelling ratio at pH 2 and above pH 5, but the swelling ratio at pH 4 was relatively small. The difference in the swelling degree in various pH media was due to the formation of a polyelectrolyte complex containing oppositely charged polymers. [Figure not available: see fulltext.]