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A Nano-sized Trojan Horse

15 June 2005 (All day)
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Trick-and-treat. Computer model of the nanoparticle used to attach folic acid to methotrexate.

Getting a cat or dog to swallow their medication usually involves a bit of trickery: the pill must be wrapped in something tasty. Now researchers are using a similar strategy to combat cancer. Scientists have developed a tiny polymer that has an irresistible treat for cancer cells at one end and a deadly poison at the other.

Because cancer cells replicate faster than normal cells do, they have a greater appetite for the vitamin folic acid, or folate. So researchers have tried tying folate directly to the cell toxin methotrexate. But keeping the two together has been an on-going challenge, especially in the bloodstream.

To solve the problem, University of Michigan nanobiotechnologist James Baker and colleagues bound both substances to nanoparticles called dendrimers that look like tiny trees. Less than 5 nanometers in diameter, the nanoparticles are small enough to slip through openings in cell membranes. When the researchers injected the conjugate into folate-deprived mice with human epithelial cancer, it was 10-times more effective at killing cancer cells than methotrexate alone and as little as 2% as toxic. The team publishes its findings today in Cancer Research.

"This paper represents an important milestone in the application of nanotechnology to the war on cancer," says biomedical engineer Gregory Lanza of Washington University in St. Louis, Missouri. But, he adds, "the model itself isn't yet relevant to people" because of the folate deprivation of the mice.

Related sites
The study
Baker's home page

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