A series of semi-interpenetrating, polymer
network (semi-IPN), hydrogel beads, composed of calcium
alginate (Ca-alginate) and poly(N-isopropylacrylamide)
(PNIPAAM), were prepared for a pH/temperature-sensitive
drug delivery study. The equilibrium swelling showed the
independent pH- and thermo- responsive nature of the
developed materials. At pH¼2.1, the release amount of
indomethacin incorporated into these beads was about 10%
within 400 min, while this value approached to 95% at
pH¼7.4. The release rate of the drug was higher at 37 8Cthan
that at 25 8C and increased slightly with increasing
PNIPAAM content. These results suggest that the Caalginate/
PNIPAAM beads have the potential to be used as
an effective pH/temperature sustainable delivery system of
bioactive agents
