A new synthesis pathway for colloidal silica spheres coated with crystalline titanium oxide and its comparative cyto- and genotoxic study with titanium oxide nanoparticles in rat osteosarcoma (UMR106) cells

[Display omitted] ► New synthesis of spherical particles with silica core and anatase shell (SiO2@TiO2). ► Induction of cyto- and genotoxicity of SiO2@TiO2 and TiO2-NP in UMR106 cells. ► Reduced cell viability for >0.5μgmL−1 SiO2@TiO2 related to delayed cell division. ► Decreased cell proliferation for >25μgmL−1 SiO2@TiO2 associated with high ROS level. ► Declined cell proliferation for >10μgmL−1 TiO2-NP associated to increased ROS level. Spherical particles with an amorphous core of silica and a crystalline shell of titanium oxide (SiO2@TiO2) formed in a three-step procedure, being the last step a mild chemical treatment. SiO2@TiO2 had a shell with pores (micro and mesopores) permeating between TiO2 nanocrystals (anatase) and a solid core of amorphous silica. The spheres had an outstanding specific surface area (300m2g−1). A cyto- and genotoxic study of SiO2@TiO2 and titanium oxide nanoparticles (TiO2-NP) on UMR106 cells with 24h exposure showed that SiO2@TiO2 colloidal particles were less toxic than TiO2-NP.