The technique has been devised by nanoengineers and the researchers have demonstrated for the first time how micromotors can be used to treat a bacterial infection in the stomach. The development presents the potential for a new wave of medical technology, and the application will appeal to many research centers and medical technology companies.
The micromotors are tiny vehicles; each device is only the size of half the width of a human hair. The motors can swim rapidly throughout the stomach and at the same time neutralize gastric acid and then release their cargo of antibiotics at the required pH. The video below shows the micromotors in action:
Video by the Laboratory for Nanobioelectronics at UC San Diego.
To test out how the micromotors might work the researchers used laboratory animals. The mouse model was tested using clarithromycin as a model antibiotic and the bacterium Helicobacter pylori as a model disease. Helicobacter pylori are linked to the development of duodenal ulcers and stomach cancer, although 8 out of 10 people with the organism are asymptomatic and it is estimated that over half the world’s population harbor H. pylori in their upper gastrointestinal tract.
The reason for developing a micromotor-enabled delivery approach was to overcome the problem with acid-sensitive drugs. Gastric acid can be destructive to many orally administered drugs (including antibiotics). To overcome this, medicines required to treat bacterial infections of the gut need to be combined with additional substance called a proton pump inhibitor (which functions to suppress gastric acid production). These inhibitors, however, carry adverse side effects such as headaches and fatigue.
The alternative developed is the micromotor, which overcomes the effect of the gastric acid by having a built-in mechanism to neutralize gastric acid. Each micromotor is formed from a spherical magnesium core coated with a layer of titanium dioxide (which provides protection from the gastric acid). Beneath this there is a layer of the required antibiotic. There is also an outer layer of a positively-charged polymer (chitosan) which allows for the motors to stick to the stomach wall. Propulsion is provided by the gastric acid itself. Lead researcher Dr. Berta Esteban-Fernández de Ávila told Controlled Environments magazine: “It’s a one-step treatment with these micromotors, combining acid neutralization with therapeutic action.”
The findings have been reported to the journal Nature Communications. The research paper is titled “Micromotor-Enabled Active Drug Delivery for In Vivo Treatment of Stomach Infection.”
