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New Evidence Nanotubes Aren’t Toxic To Humans?

by Editor1 last modified February 27, 2008 - 14:44

Researchers at Stanford University are holding out the best evidence to date that carbon nanotubes do not accumulate in living organs. The finding, based on experiments with mice, could prove especially meaningful to research projects which look at using nanotechnologies to detect and treat diseases in humans, such as cancers.

New Evidence Nanotubes Aren’t Toxic To Humans?

Stanford's Hongjie Dai, Ph.D reports findings that nanotubes may harmlessly and rapidly pass through organs.

A group of researchers at Stanford U. and the Center for Cancer Nanotechnology Excellence Focused on Therapy Response have found that carbon nanotubes leave the body primarily through the feces, some by way of the urine. The results of the study were published recently in Proceedings of the National Academy of Sciences of the United States of America

Carbon nanotubes have shown real promise as highly accurate vehicles for delivering antitumor agents into malignant cells. Even more important, the nanotubes, by simply remaining in the organs for a long time, did not prove toxic to the mouse in the experiments. “None of the mice died or showed any anomaly in the blood chemistry or in the main organs,” said Hongjie Dai, Ph.D., one of the research authors. “They appear very healthy, and they are gaining weight just like normal mice. There’s no obvious toxicity observed.”

Stanford investigators’ used Raman spectroscopy to monitor the location and concentration of carbon nanotubes in the mouse body. Carbon nanotubes offer distinctive Raman signals. The findings dispute previous studies of how the body retains nanotube materials, which were based on detection methods that relied on attaching fluorescent labels or spectroscopic tags. Using Raman spectroscopy also enabled the investigators to monitor how long the nanotubes remained in circulation, according to a summary of the work which appeared in Physorg.com.

Dr. Dai is one of the world's leaders in carbon nanotube synthesis, characterization and device applications. He has pioneered patterned synthesis of nanotubes to obtain controllable nanotube architectures. The latest data showed that coating carbon nanotubes with polyethylene glycol (PEG) produced nanotubes with circulating lifetimes of about 10 hours, which is suitable for drug and imaging agent delivery purposes, Dr. Dai added.