The research team took DNA from a virus and turned it into a sort of DNA sheet. That sheet was then loaded with an enzyme called thrombin -- a chemical that can clot blood -- and the sheet was then rolled into a tube, with the thrombin kept protected inside. To the ends of that DNA tube, the researchers attached small bits of DNA that specifically bind to a molecule found in tumor cells, and they served as a kind of guide for the DNA nanorobots. The idea is that once the nanorobots are introduced into an organism, they'll travel around and when those guiding bits of DNA come into contact with those tumor-associated molecules, they'll attach. Then, the DNA tube will open up, exposing the thrombin within. That thrombin will then clot the blood supply to the tumor, effectively cutting off its nutrients and ultimately killing it.

To test their nanorobots, the researchers injected them into mice infected with human breast cancer cells and human ovarian cancer cells as well as mouse models of human melanoma and lung cancer. In each case, the nanorobots extended the life of the mice and slowed or reversed tumor growth. Further, in the case of the melanoma model, the nanorobots appeared to be able to prevent the spread of melanoma to the liver and with the lung cancer model, the lungs even showed an ability to begin repairing themselves once the tumor growth had slowed.

Of course, the ability to treat tumors would be moot if the nanorobots themselves posed a risk to people. But the team showed that the bots didn't clot blood outside of the tumors and they didn't trigger any significant immune responses in either mice or pigs.

While they're still experimental and haven't been tested in humans, these nanorobots show a lot of promise for treating cancer. "Our research shows that DNA-based nanocarriers have been shown to be an effective and safe cancer therapy," Guangjun Nie, one of the researchers on the project, said in a statement. "We are currently working with a biotech firm to translate this revolutionary technology into a viable anti-tumor therapeutic."

The research was published today in Nature Biotechnology.