MIT study finds new way to dissolve stents, staples—potentially replacing surgical removal

In a tongue-twisting new prospect for the medtech industry, researchers from MIT have developed devices that can disintegrate on demand.

They described the discovery in a study published in the journal Advanced Materials earlier this month. It relies on the use of eutectic gallium-indium (EGaIn), a liquid metal alloy of gallium, to help break down medical devices made from solid aluminum.

“It’s known that certain combinations of liquid metals can actually get into the grain boundaries of solid metals and cause them to dramatically weaken and fail,” said Vivian Feig, Ph.D., a postdoc student at MIT and lead author of the paper. “We wanted to see if we could harness that known failure mechanism in a productive way to build these biomedical devices.”

Researchers in the lab of senior author Giovanni Traverso, M.D., Ph.D., an assistant professor of mechanical engineering at MIT, were originally developing metal devices that could stay in a patient’s digestive tract to administer drugs over the course of several days or weeks. They quickly ran into the issue of removing the devices without requiring surgical procedures, the current standard—and thus the device-dissolving project was born.

Gallium is among the elements that’s known to cause liquid metal embrittlement, and aluminum is among those known to be susceptible to it. In addition to breaking through the grain boundaries of a metal to cause fractures, as Feig described, the dissolvers also prevent the dissolvees from forming a protective oxide layer on their surfaces, further speeding up the degradation process, according to the researchers.

They put the concept to the test by building staples, stents and a drug delivery device for the GI tract out of aluminum. They then exposed the devices to EGaIn, either by painting a coat of the liquid metal onto a device or creating nanoparticles and microparticles of the alloy, then administered those to an ingested device.

Both applications were successful, the research team reported, with the aluminum devices breaking down within minutes of being exposed to gallium-indium.

“It’s a really dramatic phenomenon that can be applied to several settings,” said Traverso, who is also a gastroenterologist at Brigham and Women’s Hospital. “What this enables, potentially, is the ability to have systems that don’t require an intervention such as an endoscopy or surgical procedure for removal of devices.”

Before liquid metal embrittlement can completely replace surgical removals, however, more testing is needed. For one, though the researchers’ toxicity studies showed that even large doses of gallium-indium were nontoxic to rodents, they noted that they would need to conduct more studies before labeling the element as safe for humans, too.

Additionally, in what Feig described as an “exciting” exploration, the team is already working on applying the concept to other potentially dissolvable metals like nitinol, an alloy of nickel and titanium, that are used more commonly in esophageal stents and other medical devices.