Development and In vitro Anticancer Evaluation of Self-Assembled Supramolecular pH Responsive Hydrogels of Carboxymethyl Chitosan and Polyoxometalate

Self-assembled supramolecular pH-responsive hydrogels of carboxymethyl chitosan (CMCh) and the trilacunary heteropolytungstate salt Na-12[alpha-P2W15O56]center dot 24H(2)O generating the free polyanion P2W15 in solution, have been synthesized via electrostatic interactions. Benzoyl peroxide (BPO) was used as initiator for grafting poly (methacrylic acid) on polymer skeleton. The developed transparent hydrogels were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD) and thermal analysis including thermogravimetric analyses and differential scanning calorimetry (TGA/DSC) and the results confirmed the successful hydrogel formation. The dynamic swelling index and the controlled release pattern of the prepared hydrogels were evaluated at pH1.2 and 7.4. The maximum swelling index and polyanion release were observed at pH7.4. Different mathematical models including first order, zero order, Korsmeyer-Peppas model and Higuchi model were applied and suggested that the release of encapsulated P2W15 follows the super case transport-II mechanism and zero order kinetics. An evaluation of the anticancer activity and cytotoxicity profiling showed that both encapsulated P2W15 (hydrogel) and free P2W15 possessed a good, dose-dependent anticancer activity against MCF-7 and Hela cells, with only minimal cytotoxic effects on normal cells (Vero).