Size-dependent biodistribution of carbon nanohorns in vivo.

Carbon nanotubules, such as nanotubes and nanohorns, are potentially useful as drug delivery or hyperthermia agents for cancer therapy. However, the biokinetics of variously sized nanocarbons are important for their medical application and risk assessment. To examine the time course of the biodistribution of carbon nanohorns (CNHs) in mice, CNH aggregates of 100nm (L-CNHs) or CNHs of 30-50nm (S-CNHs) were dispersed with lipid polyethylene glycol and administered to mice through tail vein injection. Histological observation revealed that S-CNHs accumulated more slowly than did L-CNHs in the liver and spleen. The accumulation of L- and S-CNHs in spleen reached saturation within 1 and 48h, respectively, and the accumulation in liver reached saturation within 48h and >7days, respectively. CNHs did not accumulate appreciably in the lung, skin, or kidney. Histologic, hematologic, and immunologic (IL-6, TNF-α, and IFN-γ) tests did not reveal obvious toxicologic lesions at any time point. FROM THE CLINICAL EDITOR: In this study the biodistribution and accumulation characteristics of small and large carbon nanohorns were characterized in mice. Data demonstrate slower accumulation of small carbon nanohorns in liver and spleen, no accumulation in skin, lung, or kidney, and no obvious hematologic or immunologic toxicity.