It sounds like science fiction but researchers have recently succeeded in treating cancerous tumours in mice using microscopic ‘nanorobots’ or ‘nanobots’ injected into the animals’ bloodstream. Results from the joint project involving researchers from Arizona State University and the and the Chinese Academy of Sciences’ National Center for Nanscience and Technology were recently published in the Nature and Biotechnology journal. It is the first time that this kind of tiny, blood cell-sized bot has been demonstrated to be able to successfully target tumours with the confirmed result of shrinking them and stopping their spread.

The nanobots are of course too small to be ‘robots’ in the mechanical or electronic sense. Rather they are bioengineered structures created from ‘DNA sheets’ – flat, rectangular strips of DNA. Miniscule blood clotting enzymes called thrombin were attached to the surface of the biological material, then wrapped into a cylinder with the enzymes inside. The DNA the nanobots are made from targets, or is attracted by, a specific kind of protein only found in denser concentrations on the surface of tumour cells. When it reaches them in the mice’s blood stream, the thrombin was released, clotting blood around the tumour, cutting it off from the flow. This starves the tumours, shrinking them, and also prevents the cancerous cells from travelling and spreading new tumours elsewhere in the bodies of the mice.

Nanobots could also theoretically be used to transport other enzymes or substances depending on requirements. As well as fighting cancers it is hoped the new biotechnology could also be utilised to unlock inaccessible blood vessels, take biopsies or record the level of chemicals in different parts of a body.

Because the 0.1-10 micrometre (1 micrometre is a millionth of a metre) nanobots are far to small to be fitted with a motor, chip or sensor, steering them to the right place in the body to fulfil their mission is a challenge. Options being explored include the use of ultrasound to steer nanobots against the blood flow or for them to be carried on bacteria or viruses. To be effective and for scientists to know if they have delivered their load, nanobots also have to somehow be tracked after they have been sent into a body so they can subsequently be safely removed along with any tissue that has been disrupted. The solution to this intricacy has not yet bet been hit on but one option is biodegradable nanobots.

Nanomedicine is still a facet of biotechnology at an early stage of development. As well as still striving to overcome challenges such as getting nanobots to the right place and then safely removing them, the science must also become more cost effective if it is to be of practical, widespread clinical use. They must also be able to achieve things human surgeons cannot rather than simply provide an alternative methodology to the scalpel.

Despite the many questions that remain around nanomedicine, hopes around its potential impact are high. However, fitting the economic framework that medicine has to consider is one key element to future development. Criticisms have recently been made that surgical procedures that use robot-assistance are often more expensive than traditional surgery with comparable end results.