Delivery to any point
Artificial microtubules deliver drugs, moving even against the flow in the bloodstream
Tatiana Matveeva, "Scientific Russia"
The technology developed by a group from the United States and Switzerland may one day facilitate the delivery of drugs through the bloodstream to treat clogged vessels or cancerous tumors, reports University of Pennsylvania. The results are published in the journal Nature Machine Intelligence (Gu et al., Artificial microtubules for rapid and collective transport of magnetic microcargoes).
Researchers have studied the potential of micro-robots to "float" in the bloodstream to direct drugs exactly where they are needed. The disadvantage of this approach is that free-floating micro-robots hardly overcome the complex fluid flows that exist inside the human body. As a result, the particles that need to be delivered are often dispersed.
New artificial microtubules can overcome this limitation. They are made according to the type of microtubules in living cells, which are part of the cytoskeleton and use molecular motors to "drive" vesicles through them to different places in the cell. These engines find a way to cope with fluctuations in flow in blood vessels and other parts of the body.
Scientists have tried to recreate a similar mechanism in an artificial microtubule. Its thin fibers, consisting of cross-linked polymers (so that the microtubule was elastic), were sealed with nickel magnetic plates located at certain distances, like steps. Microtubules as wide as 80 microns can slip through narrow blood vessels.
The use of a rotating magnetic field around artificial microtubules turns nickel steps into magnets, along which a load of metal microrobots "rides" one after another.
"We put microtubules in a rotating magnetic field, like in an MRI. If you rotate the field slowly, the particles move slowly, and if you rotate faster, the particles also accelerate," the authors report.
Scientists have discovered a "golden mean" in the strength of the magnetic field. Too fast rotation caused the particles to slide along the surface and disperse from the microtubule.
In experiments, the research team found that microparticles can move along the microtubule fiber even when exposed to strong fluid flows that repeat the dynamics of blood flow. Compared to existing technologies, the delivery of microloads was an order of magnitude faster. And the precise adjustment of the magnetic field ensured the exact delivery of cargo to the right place, even in a complex network of ships.
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