Thousands of microscopic robots that are activated in our intestines, our veins, our organs, to come to treat, remove or repair: one would think of a science fiction scenario. Yet the dream of such non-invasive medicine may be coming true.
More and more micromotors, particles of the order of ten micrometers, capable of evolving autonomously and of responding to stimuli from their environment by changing their shape or activity, are being developed and tested in laboratory. These microswimmers made of biocompatible and biodegradable materials exist in many forms. They can travel through the human body to their target (a tumor or a thrombosis, for example), where their function is activated by an external signal or by an intrinsic change in physico-chemical conditions. Enough to deliver drug molecules or cells directly to the desired location, perform microsurgery or microbiopsies, detoxify or unblock thrombosis. All with processes that are neither toxic nor invasive.
These micromotors can be administered intravenously or orally, encapsulated in capsules and released into the intestine, where they can target lesions. For the moment, it is the oral route that is the most tested in the laboratory, although the venous route allows access to a greater number of organs.
To follow these microswimmers in the body, various medical imaging techniques can be used. Photoacoustic tomography, which has previously been used in micromotor tracking experiments in the gut of live mice, is a non-invasive hybrid imaging technique that combines light excitation and acoustic sensing. This technique allows both good resolution and good tissue penetration. Other techniques are being considered, such as magnetic resonance imaging. However, there are still challenges to be met: the techniques used for these studies, carried out on mice, which have only a few centimeters of tissue, will not necessarily give the resolution expected on humans, at a larger size.
We must therefore not declare victory too quickly. Research is still in its infancy when it comes to micromotors. Many laboratories around the world are developing these robots, but too few are tested on mice and none have yet reached the clinical trial stage. We are therefore impatiently awaiting the development of these medical techniques which could revolutionize non-invasive medicine.
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