Micromotors successfully deliver drugs to treat stomach bacterial infections

Findings published in Nature Communications from nanoengineers at the University of California San Diego, have demonstrated the success of drug delivery by micromotors to treat bacterial infections in the stomach.

The miromotors, which are most made of biodegradable materials, offer a novel delivery method for the treatment of stomach and gastrointestinal tract diseases. Challenges in this treatment area include the acidic environment, leading to degradation of medicines before they can be effective.

Using the micromotors, drugs can be transported through the stomach and released at a desired pH as a result of built in mechanism that can neutralise gastric acid. The research, which was a collaboration between the research groups of professors Joseph Wand and Liangfang Zhang at the UC San Diego Jacobs School of Engineering, is the first example of this drug delivery method in the treatment of bacterial infections.

“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 at UC San Diego and a co-first author of the paper.

The small drug delivery vehicles feature a spherical core of magnesium that is coated with titanium dioxide for protection, a layer of the antibiotic clarithromycin and then an outer layer of positively-charged polymer, chitosan. The outer polymer layer binds to the stomach wall, which also enhances the micromotor’s propulsion caused by the reaction of the magnesium ore with the stomach acid. Additionally, this reaction — between magnesium and gastric acid — raises the pH level of the stomach enough to enable the drug to be released. Normal stomach pH was found to return within 24 hours.

Tests of the micromotors was performed in mice with Helicobacter pylori infections. Administration of the drug delivery systems was given orally each day for a period of five consecutive days, after which the researchers looked at the bacteria levels in the mice stomachs and found that there was a reduction that was slightly better than that found in mice given the antibiotic with proton pump inhibitors.

Future studies of these devices are being planned by the researchers.