Microscopic Motors Journey Though Mice
Micromachine medicine recently saw a small victory after a lab mouse's body was successfully navigated by a tiny team of microscopic motors. The machines in question delivered a small test cargo of gold nanoparticles into the lining of the subject's stomach, proving that these advanced medicinal delivery systems are very possible.
According to a study recently published in the American Chemical Society's journal ACS Nano, this is actually an important step for micromachine progress. Prior to this, guided microbots and mico-missiles have only been tested in cell samples. This is the first time such technology has been used in a alive animal, and it was a smashing success.
The motors in question, often referred to as "micro-missiles" are conical polymer tubes that are no longer than 20 micrometres - a 50th of a millimeter. For comparison, geologists say that grains of sand range from one 16th of a millimeter to two millimeters in size.
That may seem too small to boast any kind of self-propulsion, and prior to the creation of these missiles, you would be right. Wei Gao, a researcher at the University of California who was involved in the study, explained to New Scientist that most previous self-propelled mico-motors were larger and relied on " non-biocompatible chemical fuels such as hydrogen peroxide." That made them dangerous to put in living animals, especially human patients, for fear of contamination.
The new missiles, however, are cleverly coated in harmless zinc. In stomach acid, this coating goes through a minor chemical reaction that produces bubbles, which are then forced through the end of the missile to push it forward.
And while bubble propulsion doesn't sound like it could move anything fast enough to get where it needs to go in a body, Gao and his colleagues found that the missiles moves JUST fast enough to lodge themselves in the porous lining of a stomach wall. There, a payload of drugs (or in the test's case, easily detected gold particles) can easily be delivered.
However, it is important to note that the rate of diffusion for these missiles still remains unclear, and may vary defending on what kind of medication is being so accurately delivered in the first place. That, Gao and his colleagues add, is something that they plan to investigate next.
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