Preparation and characterization of composite hydrogel beads based on sodium alginate

In this report, novel biopolymer hydrogels composed of sodium alginate (SA) and the oxidized sodium alginate (OSA) with an interpenetrating polymer network (IPN) structure were prepared by a combination of chemical and ionic cross-linking approaches. By using SA as the main raw material, OSA was obtained using sodium periodate. The gelation process of the IPN hydrogels was the formation of dual network: one gelatin network cross-linked by OSA with dihydrazide and another SA network cross-linked by Ca2+. The factors which affect its swelling properties were discussed. The best swelling ratio of the beads was 2300, and the swelling property was greatly affected by pH and preparation condition. The stability and swelling behavior of OSA/SA gel beads were better improved than the pure SA/Ca2+ system. The OSA/SA hydrogel beads with the pH sensitivity and stability will be a good candidate for site-specific controlled drug release carrier.