Cytotoxicity and physicochemical characterization of iron–manganese-doped sulfated zirconia nanoparticles by Al-Fahdawi, Mohamed Qasim, Abdullah, Rasedee, Al-Qubaisi, Mothanna Sadiq, Alhassan, Fatah H., Rosli, Rozita, El Zowalaty, Mohamed Ezzat, Naadja, Seïf-Eddine, Webster, Thomas J., Taufiq-Yap, Yun Hin