Cytotoxicity and Genotoxicity of Carbon Nanomaterials

With the recent development in nanoscience and nanotechnology, there is a pressing demand for assessment of the potential hazards of carbon nanomaterials to humans and other biological systems. This chapter summarizes our recent in vitro cytotoxicity and genotoxicity studies on carbon nanomaterials with an emphasis on carbon nanotubes and nanodiamonds. The studies summarized in this chapter demonstrate that carbon nanomaterials exhibit material-specific and cell-specific cytotoxicity with the general trend for biocompatibility: nanodiamonds > carbon black powders > multiwalled carbon nanotubes > single-walled carbon nanotubes, with macrophages being much more sensitive to the cytotoxicity of these carbon nanomaterials than neuroblastoma cells. However, the cytotoxicity to carbon nanomaterials could be tuned by functionalizing the nanomaterials with different surface groups. Multiwalled carbon nanotubes and nanodiamonds, albeit to a less extend, can accumulate in mouse embryonic stem (ES) cells to cause DNA damage through reactive oxygen species (ROS) generation and to increase the mutation frequency in mouse ES cells. These results point out the great need for careful scrutiny of the toxicity of nanomaterials at the molecular level, or genotoxicity, even for those materials like multiwalled carbon nanotubes and nanodiamonds that have been demonstrated to cause limited or no toxicity at the cellular level.