Motorized capsules burrow through mucus for oral insulin delivery
Technology that delivers insulin orally rather than via regular injections would be a game-changing advance in medical science, and MIT scientists have been working fervently toward this aim over many years. Their latest creation is a drug capsule that uses a robotic, tunneling head to burrow its way through the mucus in the small intestine, giving insulin a direct route to cells.
The difficulty in orally administering large protein drugs like insulin is tied to the inhospitable environment in the digestive tract. Conditions here are highly acidic, and even if the drugs are not degraded, they find it difficult to penetrate the mucus barrier lining the tract.
MIT scientists have been at the forefront of cutting-edge drug delivery systems designed to overcome these difficult obstacles. Their work has involved microneedle capsules that puncture intestinal tissue and others that take on the stomach lining. We’ve also seen MIT engineers develop materials that safely reside in the gut and slowly release drugs over time, and other innovative systems that activate drugs in response to light.
Called “RoboCap,” the latest system consists of a capsule with a robotic cap coated in gelatin, which dissolves in response to specific pH levels in the small intestine. This closes an onboard circuit that triggers an internal motor powered by a tiny biocompatible battery, which causes the capsule to start spinning.
The RoboCap is around the size of a multivitamin and was put to the test in pig intestines, where its spinning motion enabled it to burrow into the mucus barrier. This spinning action mechanically displaces the mucus barrier and simultaneously breaks down the compartment containing the drugs, enabling them to be released into cells lining the intestine.
In their animal experiments, the team was able to effectively deliver insulin as well as a larger peptide antibiotic called vancomycin, which is used to treat various infections. The RoboCap was able to deliver between 20 and 40 times the dosage of a standard capsule designed without the tunneling mechanism, and it safely passes through the digestive tract once its job is done. The mucus layer, meanwhile, was found to repair itself in within a few hours.
“What the RoboCap does is transiently displace the initial mucus barrier and then enhance absorption by maximizing the dispersion of the drug locally,” said Giovanni Traverso, who led the research. “By combining all of these elements, we’re really maximizing our capacity to provide the optimal situation for the drug to be absorbed.”
The experiments were carried out on the small intestine, but the researchers say the RoboCap could be deployed to release other drugs in the stomach or colon with tweaks to the gelatin coating that would enable it to dissolve at different pH levels.
The research was published in the journal Science Robotics.