David Gracias, Ph.D., a professor in the Johns Hopkins University Whiting School of Engineering, and Johns Hopkins gastroenterologist Florin M. Selaru, M.D., director of the Johns Hopkins Inflammatory Bowel Disease Center, led a team of researchers and biomedical engineers that designed and tested shape-changing microdevices that mimic the way the parasitic hookworm attaches itself to an organism's intestines.
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Made of metal and thin, shape-changing film and coated in a heat-sensitive paraffin wax, theragrippers could carry any drug for gradual release into the body. The team has published results of an animal study in Science Advances.
In a statement, Selaru said extended-release drugs often make their way entirely through the gastrointestinal tract before they've finished dispensing their medication.
"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," Selaru said. "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."
Because of their minute size, 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 and clamp onto the colonic wall. The closing action causes the six-pointed devices to dig into the mucosa and remain attached to the colon, where they are retained and release their medicine payloads. 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," Gracias said. "But these grippers are so small that batteries, antennas and other components will not fit on them."
Theragrippers, says 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."
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