Preparation, characterizations and in vitro cytotoxic activity of nickel oxide nanoparticles on HT-29 and SW620 colon cancer cell lines.

Despite the extensive implication of nickel oxide nanoparticles (NiO-NPs) in different fields such as biomedical science and industrial manufacturing, their effect on human cancer cells has not been elucidated. In this study, we report a simple process for the preparation of NiO-NPs. X-ray diffraction and transmission electron microscopy were used to characterize the surface architecture and dimension of the synthesized NiO-NPs. The average diameter of the NiO-NPs was approximately 20-25 nm. We used two human colon cancer cell lines, HT-29 and SW620, to assess the nanoparticles' cytotoxicity. The MTT assay showed that the NiO-NPs reduced cell viability of HT-29 and SW620 cell lines. The results of inverted microscopy showed the highest cytotoxic activity with 600 μg/ml concentration of NiO-NPs on HT-29 cells. Western blot assay showed the downregulation of anti-apoptotic Bcl2 and Bcl-xL proteins in HT-29 cells treated with NiO-NPs. Moreover the results demonstrated the induction of PARP (Cleaved) in NiO-NPs treated HT-29 cells which are considered the marker of apoptosis. The NiO-NPs were not demonstrated bactericidal effect on six different bacterial strains tested, implying that the NiO-NPs may not perturb the human normal gut microbiome. The results have showed the promising application of the NiO-NPs in management of cancer in near future.