Micromotor-Enabled Delivery Successful for Stomach Infection Treatment

Chemically powered micromotors, developed by the NanoEngineering department of the University of California-San Diego, successfully delivered antibiotics to the gut in a mouse model for treatment of a bacterial infection.

The treatment of H.pylori — a common bacteria found in more than half of the world’s population – marks the first time that micromotor technology was used in a living organism. The stomach, as an acidic environment, is a difficult place to administer treatment, making this success an important step.

The study, published in Nature Communications, examined the gap that remains in the moving of nano- and micromotors from test tubes to living organisms.

“The propulsion of drug-loaded magnesium micromotors in gastric media enables effective antibiotic delivery, leading to significant bacteria burden reduction in the mouse stomach compared with passive drug carriers, with no apparent toxicity,” the authors wrote.

The micromotor cores are made of magnesium microparticles, “with an average size of ~20 µm,” according to the authors, and were covered by several layers of TiO₂ coating using atomic layer deposition, which acted as a shell to maintain the shape and opening size during the propulsion.

Several other layers were added, including a layer that contained the antibiotic payload. This method of delivery was capable of retaining its shape through the stomach wall, and “perform an appreciable in vivo bactericidal activity,” according to the study.

Proton pump inhibitors (PPIs) are used to administer antibiotics normally in order to reduce the production of gastric acids and maintain the effectiveness, but PPIs cause issues in the long-term, such as headache, diarrhea, and anxiety and depression.

The micromotors in question, however, are propelled by the stomach acid chemically reacting to the coating layers of the motor, and temporarily reduce the acidic environment. They’re also adhesive to the stomach wall, allowing for local delivery of antibiotics.

“Moreover, while the drug-loaded micromotors reach similar therapeutic efficacy as the positive control of free drug plus proton pump inhibitor, the micromotors can function without proton pump inhibitors because of their built-in proton depletion function associated with their locomotion,” the authors concluded.

The propulsion method could be extended with alternative biocompatible fuels — or fuel-free activation – and would, in turn, expand the possible treatment areas to different parts of the body.

Although the technique is still in its very early stages, the team speculated that this form of delivery could open a door to use synthetic motors as a delivery system for in vivo treatment of diseases, claiming that the results could trigger “intensive” research in this area of medicine.