A corkscrew-shaped microrobot inspired by the tails of bacteria like E. coli can swim through blood vessels and help unblock clots.
at the Chinese University of Hong Kong and his colleagues inserted the robot into a synthetic vein filled with pig鈥檚 blood, and found it made blood clot-busting drugs work nearly five times better than the drug by itself.
鈥淭he helical structure is just like a propeller, so [the robot] can deliver the cargo from point A to point B,鈥� says Zhang. 鈥淚f you want to deliver some other thing that鈥檚 not a drug, that鈥檚 also possible. For example, therapies based on stem cells, or localised heating to kill cancer cells.鈥�
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The researchers used magnets both to rotate the microrobot鈥檚 corkscrew-shaped rotor and to drag the robot through the blood vessel. To follow and guide its path, Zhang and his team used Doppler tracking, in this case to bounce sound waves off blood cells and measure the reflections. A computer then mapped聽the shift in frequency, just as an ambulance siren changes in pitch as it moves away, to determine the robot鈥檚 movement.
After navigating the machine to the blood clot, the robot released a standard clot-breaking drug, tPA, and its rotor helped to circulate the drug around the blockage site. The researchers think delivering the drug this way may break up clots more effectively and reduce the danger of creating large fragments that could cause blockages downstream, which is a risk with drug treatment alone or catheter-based treatments.
鈥淭he ability that they have to steer the robot in in-vitro environments is quite nice,鈥� says at University College London. 鈥淭he challenges are in finding out whether this will fulfil unmet clinical needs further down the line and how you get there as well.鈥�
Although the robot proved capable of moving both upstream and downstream and at different flow rates, it is unclear how well it would work in the wide variety of environments in the human body, as well as which types of clot it might be best at unblocking. It might be most useful, Zhang suggests, in shorter blood vessels, as navigating long distances through the body is technically challenging.
Zhang says his team intends to trial the robot in conditions that more closely resemble those in humans soon, but that proving its safety in a medical setting is paramount.
ACS Nano
