Synthesis and controlled release of curcumin-β-cyclodextrin inclusion complex from nanocomposite poly(N-isopropylacrylamide/sodium alginate) hydrogels

Inclusion complex of curcumin with beta-cyclodextrin (Cur-beta-CD) was prepared using coprecipitation method. Stoichiometric ratio between curcumin and beta-cyclodextrin was found to be 1:2 with an association constant of 3.80 x 10(8) M-2 using Benesi-Hildebrand method. Inclusion complex formation was confirmed by FTIR and DSC analyses. Water solubility of curcumin increased from 0.00122 to 0.721 mg mL(-1) with the inclusion complex formation. Release of the inclusion complex from the nanocomposite and conventional poly(N-isopropylacrylamide/sodium alginate hydrogels crosslinked by nanoclay and N,N '-methylenebis(acrylamide) (BIS), respectively, were investigated in simulated gastrointestinal conditions. Swelling ratio and cumulative release were dependent on the hydrogel composition and pH. At pH = 1.2, hydrogels showed the lowest release ratio, but at pH = 6.8 highest swelling ratios were attained. The swelling ratio and cumulative release decreased with increasing the nanoclay content in nanocomposite hydrogels. On the contrary, as the ratio of BIS in the conventional hydrogels increased, the swelling ratio and cumulative release increased. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47554.