Carbon nanotubes not toxic for mice

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A new pilot study has found that single-walled carbon nanotubes are not toxic to mice, even after a period of four months. The result means that SWNTs might not be toxic to humans either and could one day be used for applications such as imaging and therapy. However, more detailed work needs to be done before this can be confirmed with any certainty.

SWNTs could be used in a host of biomedical applications, including drug delivery, imaging and destroying tumours. But scientists still do not know whether the nanomaterials are toxic and to what extent.
A new study led by Sanjiv Gambhir and colleagues at Stanford University in California has shown that SWNTs injected into the bloodstream of mice are not toxic to the animals. The researchers obtained their results by comparing two groups of five mice, one group that had been administered with between 50 and 150mg of SWNTs, and one that had not. They monitored the mice' body weight, blood pressure, blood cell counts and the amounts of electrolytes present in the bloodstream. At the end of four months, the mice were then killed and their tissues analyzed.

While there were some minor differences, the scientists found no major evidence of toxicity. The researchers did find SWNT particles in the liver Kupfer cells – but these cells are part of the reticulo-endothelial system and "gobble" up large particles in the body, so this was not surprising.

Gambhir stresses that these results must be interpreted with caution since the study was performed on a limited number of mice and for specific doses of SWNTs. "However, it does set the groundwork for future studies to see if nanotubes will indeed be safe for eventual human use," he told nanotechweb.org. "This is important because nanotubes have a lot of potential as imaging and drug-delivery agents."

The team now plans to study a larger number of mice, and other animals.

"People are sometimes scared by nanotechnology," continued Gambhir "especially using it on humans. We must continue with the type of study performed here to prove the safety of these strategies."



Source: NanoTechWeb