Fullerenes (C60) represent important carbon
nanoparticles, widely investigated for diagnostic and
therapeutic uses, mainly because they are characterized
by a small size (between 7 and 10A ° ) and a large surface
area. The cytotoxicity of two fullerene derivatives,
functionalized by 1,3-dipolar cycloaddition of azomethine
ylides to the C60 cage (1 and 2), the mechanism of
cellular uptake (studied with a fluorescein-bearing
derivative of 1, hereafter called derivative 3), and the
intracellular distribution are the subject of this work.Cell
cytotoxicity on human mammary carcinoma cell line
(MCF7), evaluated with the MTT test and further
confirmed by a flow cytometry approach with DiOC6
and PI probes, showed that derivative 1 was free of
necrotic or apoptotic effects even after a long lasting cell
exposure. Cell uptake and internalization of derivative 3
reach their zenith within 12 h after treatment, with a
tendency to persist up to 72 h; this process was evaluated
by flow cytometry and confirmed by confocal microscopy.
Thus, it appears that a compound such as derivative
1 may be unspecifically taken up by MCF7 cells, in
which it distributes throughout the cytoplasm, apparently
avoiding any co-localization within the nucleus and
secretory granules. These results suggest a strong
interaction between the tested fullerene and mammalian
cells and a significant ability of this compound to enter
tumor cells, therefore resulting to be a suitable vector to
deliver anticancer agents to tumor cells.
