Direct imaging of single-walled carbon nanotubes in cells

The development of single-walled carbon nanotubes for various biomedical applications is an area of great promise. However, the contradictory data on the toxic effects of single-walled carbon nanotubes1, 2, 3, 4, 5, 6, 7, 8, 9, 10 highlight the need for alternative ways to study their uptake and cytotoxic effects in cells. Single-walled carbon nanotubes have been shown to be acutely toxic1, 2, 3 in a number of types of cells, but the direct observation of cellular uptake of single-walled carbon nanotubes has not been demonstrated previously due to difficulties in discriminating carbon-based nanotubes from carbon-rich cell structures. Here we use transmission electron microscopy and confocal microscopy to image the translocation of single-walled carbon nanotubes into cells in both stained and unstained human cells. The nanotubes were seen to enter the cytoplasm and localize within the cell nucleus, causing cell mortality in a dose-dependent manner.