Tissue Sites of Uptake of14C-Labeled C60

This paper describes thein vivobehavior and potential metabolism of C60and a more water-soluble quaternary ammonium salt-derivatized C60. In both cases, a14C-labeled fullerene core was utilized for the target molecules that were intravenously injected into female Sprague–Dawley rats. The14C-labeled C60(*C60) was rapidly (within 1 min) cleared from the circulation and the majority of the *C60accumulated in the liver (90–95%). *C60was not eliminated from the liver over the 120-h period of this study. Our results also suggest that C60is not metabolized by the typical oxidative patterns characteristic of other polycyclic aromatics. Therefore, although not acutely toxic, use of C60, or its derivatives that could be cleaved back to the parent C60in vivo, would likely lead to long-term fullerene accumulation in the liver. The uptake of *C60and14C-labeled ammonium salt-derivatized C60(1)by human keratinocytesin vitroshowed that while both *C60and1are readily taken up by cells,1accumulates more slowly. Additionally, while C60, at rather high concentrations (2.0 μM) and over extended periods of time (8 days), is able to inhibit the growth of human keratinocytes by about 50%, this effect showed little, if any, photoinducability.