Preparation and properties of thermo-sensitive hydrogels of konjac glucomannan grafted N-isopropylacrylamide for controlled drug delivery

A thermo-sensitive hydrogel designed for controlled drug delivery was prepared and its properties were studied. The hydrogel was made of konjac glucomannan (KGM), copolymerized with N-isopropylacrylamide (NIPAAm) and crosslinked by N,N-methylene-bis-(acrylamide) (BIS). Several key parameters influencing the equilibrium swelling ratios of the hydrogels were studied. The swelling ratio was mainly controlled by the content of BIS, and influenced by the ratio of NIPAAm/KGM, slightly. It was possible to control the degree of swelling of the gels by changing crosslinking density of the polymer. The gels swelling ratio has possessed sensitive response to the environmental temperature. In vitro release of model drug bovine serum albumin (BSA) was studied at 20 degrees C and 37 degrees C in phosphate buffer solution (PBS) of pH 7.4. The accumulative release percentages are nearly 80% and 30% after 5 h at 20 degrees C and 37 degrees C, respectively.