Quantifi cation of Whole Body and Excreted Carbon Nanohorns Intravenously Injected into Mice

With the increase in the projected use of nanocarbons, such as carbon nanohorns (CNHs), carbon nanotubes (CNTs), and nanographenes, in medicine, the biodegradation and excretion of these materials has attracted increasing interest. Here, the excretion and pharmacokinetics of Gd2O3 nanoparticle labels encapsulated within CNHs after their intravenous injection into mice is studied. The results show that CNHs quantitatively changed with the postinjection time in blood vessels, livers, and other organs. About 40% of the injected CNHs are lost from the mouse body at a postinjection time of 30 d; 15% are excreted in feces, most likely via the bililary pathway into the intestine, whereas the remaining 25% are inferred to be partly or completely degraded.