Stomach Acid-Powered Micromotors

stomach acid-powered micromotors

X-ray spectroscopy and Electronic microscopy images of the stomach acid-powered micromotors. Credit: Jacobs School of Engineering/UC San Diego

Researchers have conducted the first tests on stomach acid-powered micromotors in living animals. The tiny motors might one day be used as an efficient and safe way to deliver drugs.

Human micro-engineering have progressed further as we’ve learned to manufacture microscopic device. Micro-engineering opens new avenues for medical technology ranging from new ways of diagnosing diseases to better drug delivery drugs inside our bodies (Makes me think of “Fantastic Voyage“). Advances in nanotechnology have resulted in new treatment approaches and better ways to treat or diagnose diseases. New research from University of California – San Diego demonstrate another advance, the first test of a micromotor inside a living animal.

Stomach acid-powered Micromotors

The study describing the advance was published in the journal ACS Nano.

Researchers at the Jacobs school of engineering have tested the first micromotor propelled by stomach acid inside the gut of a mouse. This tiny device is about one fifth the width of a human hair, slightly larger than five micro meters. In this study researchers wanted to test if these tiny micromotors are safe to use inside living beings and test efficiency for drug delivery.

How Stomach acid-powered Micromotors Work

The motors are made up of “long” cones of PEDOT polymers and solid zinc. The motors don’t use any type of fuel but are instead propelled by the chemical reaction of stomach acid with the zinc on the micromotors. This reaction produces a steady stream of hydrogen-gas and zinc ions propelling the motors. This mode of propulsion enables the tiny motors to reach “break-neck speeds” of up to 60 micrometers per second lasting for up to 10 minutes.

The force resulting from this chemical reaction makes it possible for micromotors to lodge themselves in the stomach wall, delivering a payload of the researchers’ choosing. In this experiment researchers used a payload of gold nanoparticles a material that’s useful in many areas including imaging and as drug carriers.

The study compared micromotor delivery of gold nanoparticles with giving nanoparticles orally to mice. Researchers found that by using micromotors to deliver the “payload” they achieved nearly four times higher concentrations of nanoparticles in stomach tissue. The motors themselves aren’t dangerous to living being either. The metal Zinc is a “green” nutrient trace element used by the body and the PEDOT polymer is a known non-toxic degradable building material. To confirm the safety of the motors researchers studied the cell lining of mice stomachs, they didn’t find any toxic effects, like damage or signs of apoptosis, Cell suicides, on the cells resulting from the micromotors.

“This initial work verifies that this motor can function in a real animal and is safe to use,” said Liangfang Zhang one of the study leaders

Researchers are currently working on a way to steer the small devices making them even more useful in the future.