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.”