In this work, 1,3,5-triazine-2,4,6-tribenzaldehyde was synthesized and chosen as the cross-linking agentfor preparation of novel thermo- and pH-responsive hydrogels based on chitosan. The cross-linking pro-ceeds through formation of imine bond by reaction of amino groups of chitosan with aldehyde groupsof the cross-linker. The various amounts (6, 10, 14% w/w) of the cross-linker were used with respect tochitosan to produce three 1,3,5-triazine-2,4,6-tribenzaldehyde cross-linked chitosans. Then, their hydro-gel nanocomposites were prepared by crosslinking of chitosan with 1,3,5-triazine-2,4,6-tribenzaldehydein the presence of 0.1% and 0.3% (w/w) multi-walled carbon nanotubes (MWCNTs). The structure andproperties of the hydrogels and their nanocomposites were characterized by FT-IR,1H NMR and scan-ning electron microscopy (SEM). The swelling behavior of prepared hydrogels and their nanocompositesat different pHs and temperatures was investigated. The results showed that they exhibit a pH andtemperature-responsive swelling ratio. The swelling behavior of the prepared chitosan hydrogels wasstrongly dependent on the amounts of cross-linker and MWCNTs. In vitro controlled release behaviorof metronidazole model drug was studied with prepared hydrogels and nanocomposite hydrogels. ThepH, temperature and wt% of MWCNTs were found to strongly influence the drug release behavior of thehydrogels.
