Micromotors are self-propelled microscopic robots, measuring about the width of a human hair, designed to perform a host of biomedical tasks in the body, such as drug delivery and ablation.  However, keeping these devices intact as they travel through the body remains a hurdle. Now, a study from researchers at UCSD develops a way to encapsulate microbots into pills. The team states their pill’s coating successfully protects the devices as they traverse the digestive system prior to releasing their drug payload.  The study is published in the journal ACS Nano.

Recent studies from the lab utilized microbots coated with an antibiotic to treat ulcers in mice, leading to better results where drugs alone were used. However, it was shown body fluids, such as gastric acid and other intestinal juices, can compromise the effectiveness of micromotors, triggering the early release of their payloads with some of the micromotors getting trapped in the esophagus. The current study develops a way to protect and carry these devices into the stomach without compromising their mobility or effectiveness.

The current study develops a pill composed of lactose and maltose sugars capable of encapsulating tens of thousands of micromotors made of a magnesium/titanium dioxide core loaded with a fluorescent dye cargo. These sugars were chosen because they are easy to mold into a tablet, can disintegrate when needed, and are nontoxic. Results show these pills improve the release and retention of the micromotors in the stomach compared to those encapsulated in silica-based tablets or in a liquid solution when given to mice. Data findings show encapsulating micromotors in traditional pill form improves their ability to deliver medicines to specific targets without diminishing their mobility or performance.

Results show the microbots successfully impel in gastric fluid, providing higher cargo retention onto the stomach lining compared to orally administrated free micromotors or passive microparticles. Data findings show the micromotor pills and loaded micromotors also retain the same characteristics after extended storage in harsh conditions.

The team surmises they have combined the advantages of traditional pills with the efficient movement of micromotors to offer an innovative route for administrating microbots orally for biomedical applications.  For the future, the researchers state their work opens the door to the use of synthetic motors for in vivo treatment of diseases.

Source: Department of Nanoengineering, University of California San Diego

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