Cancer-fighting nanorobots can seek, destroy tumours

 Washington: Scientists have successfully developed nanorobots using DNA origami that can shrink tumors by cutting off their blood supply, paving the way for novel cancer therapies.

Each nanorobot is made from a flat, rectangular DNA origami sheet, 90 nanometres by 60 nanometres in size.

A key blood-clotting enzyme, called thrombin, is attached to the surface.

Thrombin can block tumor blood flow by clotting the blood within the vessels that feed tumor growth, causing a sort of tumor mini-heart attack, and leading to tumor tissue death, researchers said.

"We have developed the first fully autonomous, DNA robotic system for a very precise drug design and targeted cancer therapy," said Hao Yan, from Arizona State University (ASU) in the US.

"Moreover, this technology is a strategy that can be used for many types of cancer, since all solid tumor-feeding blood vessels are essentially the same," said Yan.

DNA origami, in the past two decades, has developed atomic-scale manufacturing to build more and more complex structures.

The bricks to build their structures come from DNA, which can self-fold into all sorts of shapes and sizes - all at a scale one thousand times smaller than the width of a human hair - in the hopes of one day revolutionizing computing, electronics, and medicine.

Until now, the challenge to advancing nanomedicine has been difficult because scientists wanted to design, build and carefully control nanorobots to actively seek and destroy cancerous tumors - while not harming any healthy cells.

Researchers including those from Chinese Academy of Sciences overcame this problem by using a simple strategy to very selectively seek and starve out a tumor.

"These nanorobots can be programmed to transport molecular payloads and cause on-site tumor blood supply blockages, which can lead to tissue death and shrink the tumor," said Baoquan Ding, a professor at National Center for Nanoscience and Technology (NCNST) in China.

To perform the study, scientists used a mouse tumor model, where human cancer cells are injected into a mouse to induce aggressive tumor growth.

Once the tumor was growing, the nanorobots were deployed to come to the rescue.

The nanorobot is programmed to only attack cancer cells, researchers said.

Once bound to the tumor blood vessel surface, the nanorobot delivers its unsuspecting drug cargo in the very heart of the tumor, exposing an enzyme called thrombin that is key to blood clotting.

The nanorobots worked fast, congregating in large numbers to quickly surround the tumor just hours after injection.