Clearance of Au nanoparticles from mice. A: Representative transmission electron microscopy images of liver tissues from PEG-HAuNS- and saline-treated mice at the 14-day time point. Au nanoparticles and pigment were found only in the PEG-HAuNS-treated mice, indicating that the pigment in the macrophages of the liver (Kupffer cells) was attributed to PEG-HAuNS. B: Au concentration (ppm) in various dried tissue samples from male (n = 3) and female (n = 3) mice at day 14 and day 90 after the first injection of PEG-HAuNS. The p values (two tailed student’s t-test) are provided in the graphs. C: Tissue concentration of Au expressed as percentage of injected dose per gram drug tissue (%ID/g) obtained from both female and male mice (n = 6). ** p < 0.01; * p < 0.05.