Evaluation of the biological influence of a stable carbon nanohorn dispersion

We examined the induction of oxidative stress by carbon nanohorns (CNHs) in vitro and in vivo. For the in vitro examination, a stable CNH dispersion was prepared and applied to human lung carcinoma A549 cells and human keratinocyte HaCaT cells. CNH was taken up into the cells by endocytosis. CNHs did not influence cell viability or colony forming ability. The intracellular reactive oxygen species level was increased in CNH exposed cells at a concentration of 1.0 mg/ml, but intracellular lipid peroxidation level was not affected by CNH exposure. The pulmonary oxidative stress induction of CNH were also examined by intratracheal instillation in rats, and showed a transient oxidative stress in the lung at a concentration of 1.0 mg/animal. Although CNH did not show any significant cytotoxicity and short term pulmonary toxicity including oxidative stress, chronic toxicity of CNH is still not clear. Therefore, for efficient application of CNH, further examinations of biological influence of CNH are necessary.