Hydrothermal Synthesis of β-Nb 2 ZnO 6 Nanoparticles for Photocatalytic Degradation of Methyl Orange and Cytotoxicity Study.

β-Nb 2 ZnO 6 nanoparticles were synthesized by a hydrothermal process and calcined at two temperatures, 500 °C and 700 °C, and assigned as A and B, respectively. X-ray diffraction, together with transmission electron microscopy, revealed that the β-Nb 2 ZnO 6 nanoparticles calcined at 700 °C ( B ) were more crystalline than the β-Nb 2 ZnO 6 calcined at 500 °C ( A ) with both types of nanoparticles having an average size of approximately 100 nm. The physiochemical, photocatalytic, and cytotoxic activities of both types of β-Nb 2 ZnO 6 nanoparticles ( A and B ) were examined. Interestingly, the photodegradation of methyl orange, used as a standard for environmental pollutants, was faster in the presence of the β-Nb 2 ZnO 6 nanoparticles calcined at 500 °C ( A ) than in the presence of those calcined at 700 °C ( B ). Moreover, the cytotoxicity was evaluated against different types of cancer cells and the results indicated that both types of β-Nb 2 ZnO 6 nanoparticles ( A and B ) exhibited high cytotoxicity against MCF-7 and HCT116 cells but low cytotoxicity against HeLa cells after 24 and 48 h of treatment. Overall, both products expressed similar EC 50 values on tested cell lines and high cytotoxicity after 72 h of treatment. As a photocatalyst, β-Nb 2 ZnO 6 nanoparticles ( A ) could be utilized in different applications including the purification of the environment and water from specific pollutants. Further biological studies are required to determine the other potential impacts of utilizing β-Nb 2 ZnO 6 nanoparticles in the biomedical application field.