“We recognized that the mechanism used by the sandcastle worm is really a perfect vehicle for producing an underwater adhesive,” Stewart said. “This glue, just like the worm’s glue, is a fluid material that, although it doesn’t mix with water, is water soluble.”
Stewart has begun pilot studies focused on delivering bioactive molecules in the adhesive that could allow it to fix bone fragments and deliver medicines to the fracture site, such as antibiotics, pain relievers or compounds that might accelerate healing.
“We are very optimistic about this synthetic glue,” he said. “Biocompatibility is one of the major challenges of creating an adhesive like this. Anytime you put something synthetic into the body, there’s a chance the body will respond to it and damage the surrounding tissue. That’s something we will monitor, but we’ve seen no indication right now that it will be a problem.”
The traditional method of repairing shattered bones is to use mechanical connectors like nails, pins and metal screws for support until they can bear weight. But achieving and maintaining alignment of small bone fragments using screws and wires is challenging, Stewart said. For precise reconstruction of small bones, health officials have acknowledged that a biocompatible, biodegradable adhesive could be valuable because it would reduce metal hardware in the body while maintaining proper alignment of fractures.
Stewart’s challenge was to devise a water-based adhesive that remained insoluble in wet environments and was able to bond to wet objects. The team also concentrated on key details of the natural adhesive solidification process — a poorly timed hardening of the glue would make it useless, Stewart said. They learned the natural glue sets in response to changes in pH, a mechanism that was copied into the synthetic glue.
The new glue, says Stewart, a bioengineer at the University of Utah in Salt Lake City, has passed toxicity studies in cell culture. It is at least as strong as Super Glue and is twice as strong as the natural adhesive it mimics, he notes.
— John Simpson