TiO2 Nanoparticles Alter the Expression of Peroxiredoxin Antioxidant Genes

Abstract

Titanium dioxide (TiO2) nanoparticles are used industrially and commercially at increasingly high levels. While toxicity is addressed prior to use, it is also important to consider the cellular response to these nanoparticles at subcytotoxic concentrations. We used PCR arrays to screen for changes to 84 different oxidative stress-related genes in response to the incubation of cells with TiO2 nanoparticles. We found that expression of four members of the peroxiredoxin family of antioxidant enzymes was altered in response to the TiO2 nanoparticles. The oxidative stress response was specific to TiO2 nanoparticles; polystyrene nanoparticles did not alter the expression of the peroxiredoxins. In addition, serum proteins adsorbed on the surface of the TiO2 nanoparticles had a protective effect. In the absence of serum proteins, TiO2 nanoparticles were cytotoxic at the same concentrations. These experiments demonstrate that protein–TiO2 nanoparticle complexes lead to a unique oxidative stress response in cells. ...