A humble marine worm may hold the key to mending bones that have been shattered: a strong adhesive that the worm uses to build its shell, and which hardens despite the worm’s watery habitat. Sandcastle worms, Phragmatopoma californica, dwell in the intertidal zone where they construct a tubelike shell by gluing together bits of sand, broken shells and other mineral debris. The glue is secreted from a special gland and hardens in less than 30 seconds underwater, forming a leatherlike consistency over several hours [Science News].
Medical engineer Russell Stewart has been working on a synthetic glue modeled on the worm’s adhesive. He thinks the worm-inspired glue could be just the thing for piecing together the small fragments of bone that result from complex breaks that must be glued within the wet environment of the body. “There’s lots of synthetic adhesives in widespread use for other things, [but] there’s no adhesives used for deep tissue repair,” Stewart said. Current remedies are primarily mechanical fixes, such as screws, pins, and plates, which can be an inefficient method for repairing highly fractured bones [The Scientist].
In 2004, researchers determined that the secret to the worm’s success is combining two highly-charged proteins with charged ions. These components bind so tightly to one another that they make a separate fluid within the water, rather than dissolving and floating away [Discovery News]. The glue seems to set permanently when triggered by the pH change that takes place when the adhesive leaves the worm’s body and is exposed to seawater. At the ongoing meeting of the American Chemical Society, Stewart announced that his team had created a synthetic version of the worm glue which is twice as strong as the natural adhesive. The synthetic successfully clamped together two wet pieces of cow bone, Stewart said.
Although tests in cell cultures show no signs of toxic properties, much more work will be done before researchers can consider testing the synthetic adhesive in humans. Stewart also hopes to make the material more biodegradable, so that as the bone heals the glue will gradually dissolve away into the body. Biological engineer Jeffrey Karp, who wasn’t involved in the new research, also notes that using the glue in the presence of blood rather than water may change the chemical reaction. But he believes that the group is off to a good start. “I think it’s a really interesting and novel approach, to better understand the biology of the sandcastle worm to create new adhesives,” Karp says. “Evolution is the best problem solver. There’s nothing that can compete with it” [Technology Review].
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Image: Russell Stewart