Shape Changing Microdevices with in Vivo Drug Release Capabilities Created

Johns Hopkins researchers have designed tiny, star-shaped microdevices that can latch onto intestinal mucosa and release drugs into the body, inspired by a parasitic worm that digs its sharp teeth into its host's intestines. The team published their findings in Science Advances.

The team called the devices theragrippers, and they are made of metal and thin, shape changing film and coated in a heat-sensitive paraffin wax.   "Normal constriction and relaxation of GI tract muscles make it impossible for extended-release drugs to stay in the intestine long enough for the patient to receive the full dose," says co-author Florin Selaru. "We've been working to solve this problem by designing these small drug carriers that can autonomously latch onto the intestinal mucosa and keep the drug load inside the GI tract for a desired duration of time."

Thousands of theragrippers can be deployed in the GI tract. When the paraffin wax coating on the grippers reaches the temperature inside the body, the devices close autonomously and clamp onto the colonic wall. The closing action causes the tiny, six-pointed devices to dig into the mucosa and remain attached to the colon, where they are retained and release their medicine payloads gradually into the body. Eventually, the theragrippers lose their hold on the tissue and are cleared from the intestine via normal gastrointestinal muscular function.

"We have seen the introduction of dynamic, microfabricated smart devices that can be controlled by electrical or chemical signals," Selaru says. "But these grippers are so small that batteries, antennas and other components will not fit on them." Theragrippers, says co-author David Gracias, don't rely on electricity, wireless signals or external controls. "Instead, they operate like small, compressed springs with a temperature-triggered coating on the devices that releases the stored energy autonomously at body temperature."