Dose dependent in vivo metabolic characteristics of titanium dioxide nanoparticles.

Nanoparticle in vivo characteristics and interactions between nanoparticles and organisms are key components of nanotoxicology. 1H NMR was used to analyze rat urine metabolites exposed to TiO, nanopartcles by intratracheal instillation in low (0.8 mg/kg), medium (4 mg/kg) and high doses (20 mg/kg). Significant metabolite (Acetate, Valine, Dimethylamine, Taurine, Hippurate, and 2-Oxoglutarate) changes were only observed in the low dose group. These compensatory changes resolve within seven days, and the results of serum biochemical assays also implied no parenchymal damages in the liver or kidney. Rats exposed to medium and high dose nanoparticles had pulmonary inflammation because most of the instilled particles aggregated into larger sizes and accumulated in lung tissue. We conclude that low dose instillation of nano-TiO, can recoverably impact metabolic function because the scattered nanoparticles can migrate from the lung to liver or kidney, but particles in higher doses will aggregate and deposit in the lung without migration.