Magnified algae with magnetic coating

Magnetic ‘microswimmers’ deployed in living body nanotechnology trial

Image credit: Magnified algae with magnetic coating. Credit: Yan et al Science Robotics 2017

The efficacy of miniaturised, wire-like medical tools was demonstrated in a proof of concept study that could have implications for the development of medical nanorobots.

Magnetic ‘nanowires’ that can be navigated into hard-to-reach crevices inside the human body to diagnose and treat illnesses have been tested on live lab rats as part of a groundbreaking ‘proof of concept’ trial that could aid engineers in creating medical nanorobots.

The tiny wire-like tools, known as ‘microswimmers’, measure only a few millionths of a metre in length – around the size of a blood cell. They can be moulded into various shapes including helices and spheres.

The structures are manufactured from ingredients including non-harmful magnetic particles and microscopic florescent algae. They can be guided through tissue via an externally applied magnetic field – essentially a tiny magnet held outside of the body.

The natural luminescence provided courtesy of the algae allows researchers to track the progress of a swarm injected into tissue close to the skin’s surface. The microswimmers are then guided into deeper parts of the body via their magnetism, as well as the body’s natural processes, and an MRI scanner is used to pick up their location once they go too deep for the luminescence to be seen.

An international team of researchers, led by the Chinese University of Hong Kong, successfully navigated a swarm of microswimmers into the stomachs of lab rats. Their findings could lead to a better way to deliver drugs, monitor disease and even carry out some types of surgical procedures in hard-to-reach areas of the body and without recourse to more invasive medical techniques.

They are an example of a “microrobotic platform that could be further developed for in vivo imaging–guided therapy”, with the proof of concept trial described as having “far-reaching significance… for the development of microrobots”, the researchers wrote in an article published in the journal Science Robotics.

They added: “Their potential for controlled navigation in hard-to-reach cavities of the human body makes them promising miniaturised robotic tools to diagnose and treat diseases in a minimally invasive manner.

However, critical issues, such as motion tracking, biocompatibility, biodegradation, and diagnostic/therapeutic effects, need to be resolved to allow preclinical in vivo development and clinical trials.”

The microswimmers were also found to release potent compounds from their algae core during degradation, which selectively attacked cancer cells while leaving healthy cells unharmed. Further research could show whether this might have potential as a form of cancer treatment.

In addition, they can sense chemical changes linked to the onset of illness within parts of the body, which makes them potentially useful as probes for remote diagnosis.

The study was carried out in collaboration with the Universities of Edinburgh and Manchester. It was supported by the Research Grants Council of Hong Kong.

Qi Zhou, of the University of Edinburgh's School of Engineering, who worked on the study, said: A small-scale robot that can be remotely guided, is easily tracked and harmlessly biodegrades, potentially overcomes many of the challenges faced by minimally invasive therapies. We hope our discoveries will pave the way for the development of useful diagnostics or treatments.”

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