ABSTRACT
Titanium dioxide [TiO[2]] nanoparticles have shown anti-tumor activity in several cancer cell lines. TiO[2] is an effective photocatalyst that needs ultraviolet [UV] light for activation. Many efforts are in progress to improve the TiO[2] photocatalytic effects by carrying out superficial alterations in its electronic structure. For this purpose, nitrogen [N] element seems to be a proper dopant to improve photocatalytic activity of this nanoparticle. In the present study, the growth inhibitory and apoptotic effects of N-doped TiO[2] nanoparticles on human K562 cells, as an experimental model of chronic myeloid leukemia [CML], were investigated and compared with those of undoped TiO[2] in both light and dark conditions. Nanocrystalline powders of N-doped TiO[2] [80 nm] were synthesized by mechanical mixing of urea with TiO[2] powders under special experimental conditions. The structure and properties of N-doped TiO[2] nanoparticles were confirmed by transmission electron microscopy [TEM], X-ray diffraction [XRD] and Brunauer-Emmett-Teller [BET] analysis. Then we investigated the growth inhibitory and apoptotic effects of these nanoparticles on leukemia K562 cells. The results showed that visible light-irradiated N-doped TiO[2] induced profound growth inhibition and apoptosis in K562 cells in a time- and dose- dependent manner. For example, N-doped TiO[2] at concentrations of 0.01 micro g/ml, 0.1microg/ml, 1 microg/ml, 5 microg/ml and 10microg/ml inhibited growth of K562 cells by 25%, 34%, 39%, 44% and 47% and viability by 11%, 22%, 30%, 35% and 38%, respectively after 48h. Furthermore, the results of DNA fragmentation assay confirmed apoptosis in treated-K562 cells after 48h. While un-doped TiO[2] did not show any inhibitory effects on the growth and viability of K562 cells. Considering the growth inhibitory and apoptotic effects of N-doped TiO[2] in human K562 cells, this nanoparticle can be a potential candidate for photocatalytic therapy in CML in the future studies.