Facile Synthesis of Zn-Doped BiO Nanoparticles and Their Selective Cytotoxicity toward Cancer Cells.

Bismuth (III) oxide nanoparticles (BiO NPs) have shown great potential for biomedical applications because of their tunable physicochemical properties. In this work, pure and Zn-doped (1 and 3 mol %) BiO NPs were synthesized by a facile chemical route and their cytotoxicity was examined in cancer cells and normal cells. The X-ray diffraction results show that the tetragonal phase of β-BiO remains unchanged after Zn-doping. Transmission electron microscopy and scanning electron microscopy images depicted that prepared particles were spherical with smooth surfaces and the homogeneous distribution of Zn in BiO with high-quality lattice fringes without distortion. Photoluminescence spectra revealed that intensity of BiO NPs decreases with increasing level of Zn-doping. Biological data showed that Zn-doped BiO NPs induce higher cytotoxicity to human lung (A549) and liver (HepG2) cancer cells as compared to pure BiO NPs, and cytotoxic intensity increases with increasing concentration of Zn-doping. Mechanistic data indicated that Zn-doped BiO NPs induce cytotoxicity in both types of cancer cells through the generation of reactive oxygen species and caspase-3 activation. On the other hand, biocompatibility of Zn-doped BiO NPs in normal cells (primary rat hepatocytes) was greater than that of pure BiO NPs and biocompatibility improves with increasing level of Zn-doping. Altogether, this is the first report highlighting the role of Zn-doping in the anticancer activity of BiO NPs. This study warrants further research on the antitumor activity of Zn-doped BiO NPs in suitable models.