Culture

The Tiny ‘Stars’ Helping to Heal

Advances in scientific research continually reach us beyond what could only once be found in Science Fiction novels and films. The 1966 film Fantastic Voyage, shrunk down a group of people and injected them into a patient’s body to repair damaged brain cells. There was a lot wrong with that film but that concept of injecting into the body a repairing device (not humans in shrink form) is one medical science has been developing.

Inspired by a parasitic worm that digs its sharp teeth into its host’s intestines, Johns Hopkins researchers in the USA have designed tiny, star-shaped microdevices that can latch onto intestinal mucosa and release drugs into the body.

When an open theragripper, left, is exposed to internal body temperatures, it closes on the intestinal wall. In the gripper’s center is a space for a small dose of a drug credit: Johns Hopkins University

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 affixes itself to an organism’s intestines.

Made of metal and thin, shape-changing film and coated in a heat-sensitive paraffin wax, “theragrippers,” each roughly the size of a dust speck, potentially can carry any drug and release it gradually into the body.

A theragripper is about the size of a speck of dust. This swab contains dozens of the tiny devices. Credit: Johns Hopkins University.

Gradual or extended release of a drug is a long-sought goal in medicine. Selaru explains that a problem with extended-release drugs is they often make their way entirely through the gastrointestinal tract before they’ve finished dispensing their medication.

Florin Selaru explained:

“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.

“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.

David Gracias said:

“We have seen the introduction of dynamic, microfabricated smart devices that can be controlled by electrical or chemical signals.

“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.”

The team published their results of an animal study the cover article in the journal Science Advances.

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