Here’s an unlikely source of inspiration for medical technology: North American porcupines. These fierce creatures have about 30,000 quills apiece. When a porcupine feels threatened or is touched directly by a predator, quills are released from the porcupine’s skin in self-defense. The quills enter a subject easily, but are extremely difficult to remove. Talk about a nuisance!
But researchers from MIT and Brigham and Women's Hospital believe these quills could be quite helpful. They published a study this week in the Proceedings of the National Academy of Sciences describing how the quills function and how researchers might exploit the quills’ unique properties to develop new types of needles, adhesives and other medical devices.
Here’s how they work: while the quill is entering tissue, barbs covering the surface of the quill act to localize the penetration forces, allowing it to tear through tissue fibers much more easily—just as a serrated knife cuts through tomato skin far more cleanly than a straight-edged knife. When it comes to the force required for pullout, the barbs act like anchors that make it difficult to remove the quill without damaging tissue.
To create needles that enter skin more efficiently, the researchers believe the quill system could be tweaked so that it penetrates tissue easily, but also detaches easily, enabling design of less-painful needles for injections.
To explore the possibility of making stronger adhesives, the researchers created a patch with an array of barbed quills on one side. They found that the energy required to remove this patch was 30 times greater than that needed for a control patch, which had quills but no barbs.
There is a great need for such adhesives, especially for patients who have undergone gastric-bypass surgery or other types of gastric or intestinal surgery. These surgical incisions are now sealed with sutures or staples, which can leak and cause complications.
"We believe that evolution is the best problem-solver," says co-author Jeffrey Karp of Brigham and Women's Hospital.