Fast responsive thermosensitive hydrogels as drug delivery systems

Ionic and non-ionic temperature sensitive hydrogels of poly(N-isopropylacrylamide) and calcium alginate were prepared as interpenetrating networks. Calcium alginate was used as a mould to prepare uniform, large size, spherical beads and then extracted to leave a macroporous structure. Swelling behaviour, and drug release kinetics of these thermosensitive hydrogels were studied in aqueous media. The swelling observations indicated that the equilibrium swelling degree of homopolymer gel increased after calcium alginate extraction, and besides calcium alginate had no effect on lower critical solution temperature (LCST). In addition, equilibrium swelling degree of copolymer composite hydrogels containing Na+, and Ca2+ cations were greater than that of the extracted hydrogel containing only monovalent cations. It was observed that, swelling kinetics of hydrogels followed a Fickian behaviour. Drug release experiments indicated that drug release from these hydrogels was fast and in Fickian manner.