When the robots reach their target and bind to its surface they spring open and deliver the enzyme which clots the blood supply to the tumour and causes it to have a mini heart attack and die. In this case, the tiny robot is folded in a tube shape around the enzyme thrombin, which can clot blood.
The worldwide team of researchers started with the goal of "finding a path to design nanorobots that can be applied to treatment of cancer in human [s]", writes coauthor Hao Yan of Arizona State University in an email to The Scientist.
Read the first-of-its-kind study (using melanoma and breast, lung, and ovarian cancer mouse models), published this week in the journal Nature Biotechnology. They were affixed with a DNA aptamer made to specifically target nucleolin, a protein only found in high concentrations on the surface of tumor endothelial cells. The next step is to investigate any damage-such as undetected clots or immune-system responses-in the host organism, he says, as well as to determine how much thrombin is actually delivered at the tumor sites.
This new technology eliminates previous issues that scientists faced with trying to create tumor-killing nanorobots.
While they're still experimental and haven't been tested in humans, these nanorobots show a lot of promise for treating cancer.
"We have developed the first fully autonomous, DNA robotic system for a very precise drug design and targeted cancer therapy", Hao Yan, director of the ASU Biodesign Institute's Center for Molecular Design and Biomimetics, declared in a statement.
The team took a rectangular piece of DNA origami sheet - measuring just 90 nanometers by 60 nanometers - and peppered it with a protein known as thrombin. Once the tumor was growing, the nanorobots - which are a thousand times smaller than a strand of human hair - were deployed.
The scientists were also able to demonstrate the bots did not cause clotting in the healthy tissues of Bama miniature pigs, calming fears over what might happen in larger animals.
Life expectancy in treated mice was 45 days, compared to 20.5 days in non-treated mice. "Moreover, this technology is a strategy that can be used for many types of cancer, since all solid tumour-feeding blood vessels are essentially the same". According to Guangjun Nie, one of the researchers on the project, "Our research shows that DNA-based nanocarriers have been shown to be an effective and safe cancer therapy".
Dr James Tour of Rice University in the USA, who was involved in last year's breakthrough with Durham University, said the "spring-loaded" nanorobot was "exciting", adding: 'It is a nano-Trojan horse!' But the results of this new study are promising - Yan and the research team are now hoping to pursue clinical testing.