Nanoengineers have developed micromotors to treat a bacterial infection in the stomach, promising a new method for treating stomach and gastrointestinal tract diseases with acid-sensitive drugs.

The in vivo operation of micromotors and this study represents the first example of drug-delivering micromotors for treating bacterial infection, using tiny vehicles, each about half the width of a human hair, swim rapidly throughout the stomach while neutralising gastric acid and then release their cargo of antibiotics at the desired pH. The findings have been published in Nature Communications.

"It’s a one-step treatment with these micromotors, combining acid neutralisation with therapeutic action," said Berta Esteban-Fernández de Ávila, a postdoctoral scholar in Wang’s research group and a co-first author of the paper.

Each micromotor consists of a spherical magnesium core coated with a protective layer of titanium dioxide, followed by a layer of the antibiotic clarithromycin, and an outer layer of a positively-charged polymer called chitosan that enables the motors to stick to the stomach wall. 

This binding is also enhanced by the propulsion of the micromotors, which is fuelled by the stomach’s own acid. The magnesium cores react with gastric acid, generating a stream of hydrogen microbubbles that propel the motors around inside the stomach. This reaction also temporarily reduces the amount of acid in the stomach, increasing the pH level enough to allow the micromotors to release the drug and perform treatment. The normal stomach pH is restored within 24 hours.