Patients could one day be diagnosed and cured of fatal diseases such as cancer through the use of tiny remote-controlled robots.

A team of scientists at the Chinese University of Hong Kong, led by Professor Li Zhang, are using a biodegradable substance called spirulina algae. Covered in an iron coating, the nanobots are controlled by magnetic fields. The coil shape of the nanobot allows it to move easily with the help of magnetic waves.

"Rather than fabricate a functional microbot from scratch using intricate laboratory techniques and process, we set out to directly engineer smart materials in nature, which are endowed with favourable functionalities for medical applications owing to their intrinsic chemical composition," Zhang said.

"For instance, because these biohybrid bots have a naturally fluorescent biological interior and magnetic iron-oxide exterior, we can track and actuate a swarm of those agents inside the body quite easily using fluorescence imaging and magnetic resonance imaging."

Not relying on a fuel source (most of which are toxic to humans) allows the nanobots to biodegrade naturally over hours or days (depending on the thickness of the iron coating). When cancer cells are exposed to the nanobots, only about 10% (of the cancer cells) manage to survive. It is harmless to other cells in the body, making it a viable solution for fighting cancer.

Nanobots fighting cancer
Nanobots could be used to diagnose and fight disease. The University of Manchester

University of Manchester professor Kostas Kostarelos said creating robotic systems that can be controlled through the body was the "holy grail" of delivery system engineering. "We are still in early days of development since any such robotic system would need to be either completely and safely degraded, or it will need to be removed or excreted from the body after it has finished its work."

"But nevertheless, our work provides the first ever example of how this could be possible achieved by degradation," Kostarelos said. "The potential of these bots for controlled navigation in hard-to-reach cavities of the human body makes them promising miniaturized robotic tools to diagnose and treat diseased which is minimally invasive."

The research is a joint venture between the Chinese University of Hong Kong, University of Manchester and University of Edinburgh. A paper on the findings was published in Science Robotics on Wednesday (22 November).