Scientists have developed cancer-fighting ‘nanorobots’ which are capable of homing in and destroying tumours without damaging healthy tissue.

The discovery, reported in the journal Nature, has been hailed as a breakthrough in nanomedicine, where nanotechnology is used to diagnose and treat diseases.

The five-year study was conducted by Arizona State University scientists in collaboration with researchers from the National Center for Nanoscience and Technology of the Chinese Academy of Sciences.

They successfully programmed the nanorobots to cut off the blood supply to specific breast cancer, melanoma, ovarian and lung cancer tumours in mice, causing them to shrink and in some cases disappear.

“We have developed the first fully autonomous, DNA robotic system for a very precise drug design and targeted cancer therapy,” said Hao Yan, director of the ASU Biodesign Institute’s Center for Molecular Design and Biomimetics and the Milton Glick Professor in the School of Molecular Sciences.

“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.”

Each nanorobot consists of a flat sheet of DNA which is 1,000 times smaller than the width of a human hair and can be folded in on itself – like origami – to make a hollow tube. The sheet has the enzyme thrombin attached to its surface which clots the blood within the vessels that feed tumour growth.

A DNA aptamer is also included which specifically targets the protein nucleolin which is generated in great quantities on tumour endothelial cells and not found on the surface of healthy cells.

After the nanorobots were injected into a mouse, they surrounded the tumours within hours. Three out of the eight mice showed complete regression of the tumours while median survival time more than doubled from 20.5 to 45 days.

Tests were also carried out on Bama miniature pigs.

“The nanorobots are decidedly safe in the normal tissues of mice and large animals,” said Guangjun Nie, a professor at the National Center for Nanoscience and Technology in Beijing.

Yan added: “The thrombin-delivery DNA nanorobot constitutes a major advance in the application of DNA nanotechnology for cancer therapy.

“I think we are much closer to real, practical medical applications of the technology. Combinations of different rationally designed nanorobots carrying various agents may help to accomplish the ultimate goal of cancer research: the eradication of solid tumors and vascularized metastases.

“The current strategy may be developed as a drug-delivery platform for the treatment of other diseases by modification of the geometry of the nanostructures, the targeting groups and the loaded cargoes.”