Specific surface area of titanium dioxide (TiO2) particles influences cyto- and photo-toxicity

► A surface area dependent cyto- and photo-toxicity of TiO2 particles is proposed. ► To exclude size effect, we used two novel particles with similar sizes. ► TiO2 particles with larger surface area could interact more with biomolecules. ► TiO2 particles with larger surface area could generate more hydroxyl radicals. ► Pre-adsorbing TiO2 particles with proteins was found to decrease toxicity effect.