Tissue distribution and excretion of intravenously administered titanium dioxide nanoparticles

As the biosafety of nanotechnology becomes a growing concern, the in vivo nanotoxicity of nanoparticles (NPs) has been drawn an increasing attention. Titanium dioxide nanoparticles (TiO(2)-NPs) have been developed for versatile use, but the pharmacokinetics of intravenously administered TiO(2)-NPs have not been investigated extensively. In the present study, the rutile-type TiO(2)-NPs with a size about 20nm were labeled with CF680 and (125)I. The labeled TiO(2)-NPs were injected in mice or rats with the concentration of 1mg/ml and the dose of 10mg/kg body weight and their tissue distribution and excretion were investigated by using ex vivo fluorescent imaging, γ-counter and TEM. The results indicated that the TiO(2)-NPs mainly accumulated in liver and spleen and could be retained for over 30days in these tissues due to the phagocytosis by macrophages. The excretion assay found that the excretory rate of TiO(2)-NPs through urine was higher than that of feces, indicating that renal excretion was the main excretion pathway of TiO(2)-NPs. Overall results of the present study provided important information on distribution and excretion of TiO(2)-NPs in vivo, which would greatly promote the pharmacokinetics and in vivo nanotoxicity research of TiO(2)-NPs.