Synthesis of chitosan-coated polyoxometalate nanoparticles against cancer and its metastasis

Three different Keggin-type polyoxometalates (POMs) [PW 12 O 40 ] 3− , [TiW 11 CoO 40 ] 7− , and [Ti 2 PW 10 O 40 ] 7− , were synthesized and then encapsulated in chitosan to prepare nanoparticles, CS-PW 12 , CS-TiW 11 Co, and CS-Ti 2 PW 10 . The synthesized nanoparticles were physicochemically characterized in terms of particle size, zeta potential, entrapment efficiency and in vitro release of the entrapped POM. The most efficient formulation was CS-TiW 11 Co, with a particle size of 105 ± 6 nm and an entrapment efficiency of 87 ± 12 (%). The CS-TiW 11 Co nanoparticles showed the highest activity when tested against tissue nonspecific alkaline phosphatase (TNAP) with IC 50 = 102.0 ± 9.68 nM. The anticancer potential of the free POMs and their nanoparticles were also studied and CS-TiW 11 Co showed the highest inhibition (IC 50 = 1.06 ± 0.09) on HeLa cells. To observe signs of apoptosis in HeLA cells, DAPI staining was performed after treatment with CS-TiW 11 Co nanoparticles. Furthermore, the reactive oxygen species (ROS) production was examined by H 2 DCF-DA dye under a fluorescence microscope. Our study revealed that CS-TiW 11 Co nanoparticles are very effective in cancer treatment and its associated metastasis especially in osteoblastic lesions with minimal adverse effects on normal cells (Vero cells). HeLa cells, before and after treatment with nanoparticles.