Worms Inspire New Bioadhesive

Sandcastle worms are pretty good chemists. Without advanced degrees, they have figured out how to biosynthesize glue components they use to build their underwater tubular shelters. Inspired by the worms, Russell J. Stewart of the University of Utah and coworkers are creating similar adhesives that might be used to make in utero surgery safer or to block blood vessels that feed tumors.

“It’s a classic example of borrowing successfully from nature,” comments biomedical sealants specialist Jeffrey M. Karp of Brigham & Women’s Hospital, in Boston.

When doctors examine or perform surgery on developing fetuses, the amniotic membranes that protect fetuses in the womb can rupture. The membranes often fail to heal, so the procedures carry a significant risk of preterm delivery.

Existing medical adhesives fall short in addressing this surgical problem. Some adhesives swell too much when they cure and may cause further damage. Others “are ineffective in the flexible, moist, and biochemically active conditions of the human body or are acutely cytotoxic,” says Nick Aldred of Newcastle University, in England, who is an expert on barnacle adhesives.

Stewart told a Division of Agricultural & Food Chemistry session at last week’s American Chemical Society national meeting that he hopes a sandcastle-worm-inspired adhesive his group is developing will provide an effective alternative for existing adhesives.

Sandcastle worms produce highly charged polyelectrolyte glue components and combine oppositely charged components enzymatically to construct their shelters. Obtaining the glue directly from the worms or producing it recombinantly hasn’t proved practical. So Stewart and coworkers instead synthesize oppositely charged polyelectrolytes and combine them to form water-immiscible polymer solutions called complex coacervates. They then apply the coacervates to biological tissues and cross-link them enzymatically to cure them into adhesives that bond to the tissues. The patented technique is in preclinical testing for use in fetal surgery.

Stewart and coworkers “have made astounding progress in quickly moving from understanding the key concepts of wet adhesion by the sandcastle worm to the point where they are able to synthesize a polymer that mimics it,” said Anne Marie Power of the National University of Ireland, who studies barnacle wet adhesion. “It could address a real surgical problem.”