Hydrothermal Synthesis of β-NbZnO Nanoparticles for Photocatalytic Degradation of Methyl Orange and Cytotoxicity Study.

β-NbZnO nanoparticles were synthesized by a hydrothermal process and calcined at two temperatures, 500 °C and 700 °C, and assigned as and respectively. X-ray diffraction, together with transmission electron microscopy, revealed that the β-NbZnO nanoparticles calcined at 700 °C () were more crystalline than the β-NbZnO calcined at 500 °C () with both types of nanoparticles having an average size of approximately 100 nm. The physiochemical, photocatalytic, and cytotoxic activities of both types of β-NbZnO nanoparticles ( and ) were examined. Interestingly, the photodegradation of methyl orange, used as a standard for environmental pollutants, was faster in the presence of the β-NbZnO nanoparticles calcined at 500 °C () than in the presence of those calcined at 700 °C (). Moreover, the cytotoxicity was evaluated against different types of cancer cells and the results indicated that both types of β-NbZnO nanoparticles ( and ) 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 values on tested cell lines and high cytotoxicity after 72 h of treatment. As a photocatalyst, β-NbZnO nanoparticles () 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-NbZnO nanoparticles in the biomedical application field.