With the recent development in nanoscience and nanotechnology, there is a pressing demand for ass... more 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.
The bulk ore carrier Apollo Seasank near Dassen Island, South Africa, on 20 June 1994 during a pe... more The bulk ore carrier Apollo Seasank near Dassen Island, South Africa, on 20 June 1994 during a period of winter storms. Approximately 10 000 African (Jackass) Penguins Spheniscus demersuswere oiled, collected and transported to the SANCCOB rescue centre; 5213 were released after cleaning, 4076 with flipper bands. We believe that most of the penguins oiled during this incident reached an island or the mainland alive, and that there was no mass mortality in the wild at the time of the oil spill. Birds from all parts of the breeding range were oiled, but most were from Robben and Dassen Islands. The overwhelming majority of released birds made the transition from the rescue centre to the wild successfully; 2652 had been resighted at breeding colonies within two years of their release; the cumulative number of birds was increasing steadily and an asymptote had not been reached by August 1996. There was a wide dispersal of released penguins, with recoveries and resightings over 1800 km of coastline between Algoa Bay and Walvis Bay.
With the recent development in nanoscience and nanotechnology, there is a pressing demand for ass... more 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.
The bulk ore carrier Apollo Seasank near Dassen Island, South Africa, on 20 June 1994 during a pe... more The bulk ore carrier Apollo Seasank near Dassen Island, South Africa, on 20 June 1994 during a period of winter storms. Approximately 10 000 African (Jackass) Penguins Spheniscus demersuswere oiled, collected and transported to the SANCCOB rescue centre; 5213 were released after cleaning, 4076 with flipper bands. We believe that most of the penguins oiled during this incident reached an island or the mainland alive, and that there was no mass mortality in the wild at the time of the oil spill. Birds from all parts of the breeding range were oiled, but most were from Robben and Dassen Islands. The overwhelming majority of released birds made the transition from the rescue centre to the wild successfully; 2652 had been resighted at breeding colonies within two years of their release; the cumulative number of birds was increasing steadily and an asymptote had not been reached by August 1996. There was a wide dispersal of released penguins, with recoveries and resightings over 1800 km of coastline between Algoa Bay and Walvis Bay.
Uploads
Papers by Lukas Nel