Using Nanocrystals, The Big Picture of Tiny Images

Quantum dots show no toxicity in animal studies

(RxWiki News) Size isn't always the best indicator of danger when it comes to cancer, and a lot of imaging technology like MRIs and CT scans use different tricks to get the best picture possible of tiny tumors.

Researchers using nanocrystals, which they call quantum dots due to their tiny size, used a shortcut to find tiny cancers using an old principle. If you can't find the honey, follow the bees. 

"Ask your oncologist about new advances in cancer treatment."

In a partnership between the University of Buffalo in New York and several hospitals in China and Singapore, scientists found that four rhesus monkeys given repeat injections of the cadmium-selenide nanoparticles did not suffer any acute health problems for the first ninety days of treatment. 

Two of the animals were monitored for a year afterwards, and the study authors reported that no adverse effects were observed for a year afterwards.

On the other hand, the report stated, in the first 90 days of treatment, the particles accumulated in the liver, spleen and kidneys of the animals and didn't appear to leave the body in significant amounts.

While the lack of acute toxicity was reassuring, the build up was worrying enough for researchers to commit their laboratory to more in-depth studies.

The press around the possibilities of using nanotechnology in medicine for both imaging and treatment has been very exciting, this study was the first so far to look at the possible toxic effects of quantum dot nanocrystals, which are relatively unstudied at this point. and a lot of speculation exists on what could go wrong.

Ruling out severe problems is the first step, and more long term studies will follow. Approval by the FDA of several nanoparticle-sized chemotherapy drugs has already taken place, but the risks and rewards of using nanoparticles in imaging studies has a higher standard to clear.

"This is the first study that uses primates as animal models for in vivo studies with quantum dots," stated coauthor Paras Prasad, PhD. "So far, such toxicity studies have focused only on mice and rats, but humans are very different from mice. More studies using animal models that are closer to humans are necessary."

The cadmium build-up, in particular, is a serious concern that warrants further investigation, according to Ken-Tye Yong, a current professor at Nanyang Technological University in China who began work on the project with Prasad in his studies at the University of Buffalo in New York.

The research was published in the journal Nature Nanotechnology on May 20, 2012.

Funding for the study was provided by the Air Force Office of Scientific Research, Singapore Ministry of Education, Nanyang Technological University, the Beijing Natural Science Foundation and the National Natural Science Foundation of China.

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Review Date: 
May 26, 2012