All forms of TiO
cause reactive oxygen species (ROS) generation. The relative lipid peroxidation of the three TiO2 nanoparticles using a fluorescent BODIPY stain in alveolar macrophages, which changes to green from red in the presence of oxygen radical damage. A: no particle control, B: NS, C: NB-1, and D: NB-2. All three nanoparticles produce some degree of lipid peroxidation indicated by the presence of green stain. In addition, intracellular ROS were measured over a 2 hour nanoparticle exposure in AM using the fluorescent tag DHE (E). All three nanoparticle types produced significant amounts of ROS, but there was no difference between the nanoparticle types indicating that oxygen radicals could not account for any difference in AM toxicity seen with NB-2 exposure.