Comparing the toxic mechanism of synthesized zinc oxide nanomaterials by physicochemical characterization and reactive oxygen species properties

► Comparative toxicity study of ZnO nanoparticles (ZnO-RT, ZnO60), synthesized in different temperature process, was performed. ► Larger ZnO (ZnO-60) is more toxic than smaller one (ZnO-RT). ► However, the size of ZnO and released Zn2+ ion were not the dominant toxic factor. Rather the toxicity of ZnO was related with formation of ROS.