The stickiness of a geckos foot has formed the basis of a waterproof glue. (/ISTOCKPHOTO )
Sea worms, jellyfish, geckos and spiders may seem unlikely muses to cutting-edge technology. But these creatures are helping stimulate medical innovations — including new adhesives, diagnostic tests and needles — that are slowly migrating from the lab to the clinic.
“Evolution is the best problem-solver,” said Jeffrey Karp, co-director of the Center for Regenerative Therapeutics at Brigham and Women’s Hospital in Boston. “Often in technology, we encounter barriers that appear to be insurmountable,” he said, but sometimes answers can be found in the most obvious place: nature itself.
Karp is a leader in the burgeoning fields of bio-inspired and biomimetic medicine, in which medical devices are inspired by or imitate nature. Five years ago, he and colleagues at MIT developed a waterproof glue based on the sticky properties of geckos’ feet. The adhesive, which might be used by surgeons to seal holes in organs and other tissue, is being tested in large animals, a step that would be followed by human trials.
In October, Karp and Bob Langer at MIT published a paper on a three-layer quick-release adhesive they are developing to protect the fragile skin of babies. Each year, 1.5 million U.S. newborns are injured because of rips and tears from tapes that hold intravenous tubes and other devices onto the skin. The elderly, too, often suffer painful abrasions from medical tape.
Karp said his team found inspiration in multilayered minerals such as mica, which form strong bonds in one direction but pull apart easily in others, and spider webs, which have sticky parts that grab prey and non-sticky parts that allow the spider to walk on them. These properties help make the glue gentle and strong at the same time. Karp says his adhesive is five to 10 times easier to remove than existing products.
To make the tape, the team developed a middle layer that has different physical properties depending on which way it’s pulled. Using a laser, the researchers etched a pattern on the in-
between layer to control how the adhesive and the backing interact. The next step is creating a prototype that will be tested in clinical trials, Karp said.
Tentacle approach to cancer
Karp and another group at MIT also came up with a microchip that uses tiny strands of DNA that grab and hold tumor cells in the bloodstream.
“We became inspired by jellyfish that have these long tentacles that extend far away from their main body,” he said. These arms expand their reach for food. “Regardless of where the food lands, they can capture it.”
The microchip can be used to count and sort cancer cells; both functions are important to determine how well chemotherapy or other treatments are working. It’s also important to know the number of cancer cells remaining after chemotherapy, so that doctors can determine how resistant the tumor is or whether another one is likely to appear elsewhere in the body.
“The key is to know which drugs the remaining cells would be most susceptible to,” Karp said. “What you really want to do is collect them and study the biology of the cells, and subject them to different kinds of chemo so you know which one is best to use.”
The microchip also counts cells 10 times faster than existing devices, giving doctors critical data more quickly, according to a study published in Proceedings of the National Academy of Sciences.
If the device works, the microchip will provide valuable information about how tumors and their treatments are progressing, according to Howard Scher, chief of medical genitourinary oncology at the Memorial Sloan-Kettering Cancer Center in New York, who was not part of Karp’s study.
“You can watch the biology of the cancer change,” he said. The device “gives you clues as to why a treatment may no longer be working.”
The scientists took short strands of DNA that bind with the targeted cancer cell surface and copied them hundreds of times. By connecting these DNA strands, they produced wispy material much longer than the cell itself. One end of the strand is connected to the microchip; the other floats free in the bloodstream. As cancer cells drift by, the strands bind to them, just as a jellyfish grabs food, Karp explained. The team is about to begin testing on patient tumor samples.
Russell Stewart, a professor of bioengineering at the University of Utah, is inspired by another marine creature: the sandcastle worm. This worm, named for its ability to assemble underwater reefs that resemble sand castles, is coveted by researchers trying to figure out how to create adhesive substances that work inside the water-heavy human body.
Making it stick
Ever tried putting on a plastic bandage in the shower? Common glues and tapes don’t stick to wet surfaces because the water prevents the glue from adhering. Super Glue and similar products are water-insoluble if you create the bond while the glue is dry, but they don’t adhere to wet surfaces.