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Self‐assembled supramolecular pH‐responsive hydrogels of carboxymethyl chitosan (CMCh) and the trilacunary heteropolytungstate salt Na12[α‐P2W15O56].24H2O 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 pH 1.2 and 7.4. The maximum swelling index and polyanion release were observed at pH 7.4. 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).

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In the present study electrostatically‐driven pH responsive supramolecular, self‐assembled hydrogels of the trilacunary Wells‐Dawson‐type 15‐tungsto‐2‐phosphate polyanion [P2W15O56]12− (P2W15) and polyethyleneimine were prepared. Crosslinking was achieved through electrostatic interactions between cationic polyethyleneimine and P2W15. The pH responsiveness was induced by acrylic acid. Benzoyl peroxide was used as an initiator, for initiating the polymerization reaction, anchoring polyacrylic acid on the polyethyleneimine skeleton. The prepared sea‐green color hydrogels were characterized by FT‐IR, SEM, XRD and thermal analysis (TGA‐DSC). The swelling index, P2W15 release studies and pH responsive properties of the developed supramolecular hydrogels were evaluated at pH 1.2 and 7.4, showing maximum swellability and release characteristics at pH 7.4. For determining the P2W15 release mechanism different mathematical models such as zero order, first order, Higuchi model and Krosmeyer‐Peppas models were applied and the results showed that embedded P2W15 release follows zero‐order kinetics. The cytotoxicity results showed that naked and embedded P2W15 exhibited dose‐dependent cytotoxicity against cancer cell lines (MCF‐7; Hela) with minimal effects on normal cells (Vero). The hydrogels developed through electrostatic interactions exhibited desirable qualities of a drug delivery system that can be used for the delivery of the embedded polyanion.