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.

Abstract Spherical particles with an amorphous core of silica and a crystalline shell of titanium oxide (SiO 2 @TiO 2 ) formed in a three-step procedure, being the last step a mild chemical treatment. SiO 2 @TiO 2 had a shell with pores (micro and mesopores) permeating between TiO 2 nanocrystals (anatase) and a solid core of amorphous silica. The spheres had an outstanding specific surface area (300 m 2  g −1 ). A cyto- and genotoxic study of SiO 2 @TiO 2 and titanium oxide nanoparticles (TiO 2 -NP) on UMR106 cells with 24 h exposure showed that SiO 2 @TiO 2 colloidal particles were less toxic than TiO 2 -NP.