Fig. 2

Lung burden analysis and clearance pattern of carbon black nanoparticles (CBNPs) in rats. CBNPs were instilled into the lungs of rats at 30, 100, and 300 µg/rat, and lung burden was evaluated at days 0, 1, 7, 28, 60, and 90 post-instillation. (A) Pulmonary deposition percentage of CBNPs by the intratracheal instillation technique used in this study. (B) The retention percentage of CBNPs over time at three different doses. (C) The actual measured concentration of CBNPs retained in the lung. (D) Bright- and (E) dark-field images of bronchoalveolar lavage cells. Note that unphagocytized particles are evident in the high-dose group (red arrows), while lower doses showed that particles are mainly located in the cytoplasm of alveolar macrophages. VEH, vehicle control. Scale bar = 30 μm. Data are mean ± standard error of the mean (SEM) (n = 4 for each group)