February 18, 2013
Bivalve Adhesive Serves As Inspiration For New Medical Breakthroughs
redOrbit Staff & Wire Reports - Your Universe Online
The mussel´s ability to cling to slippery, wet rock in even the most violent waters — all while being capable of supporting the weight of a full-grown adult — has now become the inspiration for the development of new, cutting-edge medical applications, researchers reported Friday at the annual meeting of the American Academy for the Advancement of Science (AAAS).
According to Dan Ferber of ScienceNOW, “To hold fast beneath the surging waves, mussels secrete liquid proteins that harden into a solid, water-resistant glue. What´s easy for the animals, however, has been hard for human engineers. Not even Super Glue will stick in a fish aquarium because a layer of water forms that keeps the two surfaces from bonding.”
For three decades, University of California, Santa Barbara biologist Herbert Waite and colleagues have studied exactly how the bivalve manages to accomplish this feat. They discovered that the 15 proteins that comprise the thread-like structures (known as holdfasts) that help them cling to surfaces contain a considerable amount of the amino acid dihydroxyphenylalanine (DOPA).
“DOPA is particularly abundant in parts of the proteins that face out toward the hard surface,” Ferber said. “It enables liquid holdfast proteins to solidify rapidly and stick flawlessly to wet and salty surfaces.”
Using that knowledge, he and his colleagues have been able to work on synthetically replicating the chemical for a number of different medical purposes, including “water-resistant glues that will allow doctors to attach insulin-secreting patches to the internal organs of diabetics,” McKie added.
In addition, Smartplanet´s Janet Fang reports that researchers are also working to use their knowledge of the mussel´s holdfasts to create “biocompatible glue that can seal fetal membranes.”
While prenatal surgeons are currently able to correct some birth defects in utero, “the surgery risks rupturing the protective fetal membrane prematurely, triggering premature labor,” Fang said. “There are no good adhesives on the market that can repair these fetal-membrane tears — the main reason why fetal surgery remains risky.”
The liquid proteins excreted by mussels, however, “harden into a solid, water resistant glue” that “shares the same desired properties as medical adhesives, according to Phillip Messersmith of Northwestern University.”
He and his team took Waite´s research and used it to create “a synthetic, thread-like polymer – called polyethylene glycol – that mimics the mussel protein,” Fang said. “And they tipped it with an amino acid that´s found on the parts of mussel proteins that face out toward the hard surface."
They then tested the adhesive on a 3.5-millimeter hole in the fetal membrane of a rabbit, successfully sealing the puncture. Without the glue, Fang said that only 40-percent of infant rabbits survived surgery, but the success rate jumped to 60-percent when the special substance was used in the operation.
In similar research, scientists at the Pohang University of Science and Technology in South Korea have reportedly developed a chemical Velcro that Chemistry World writer James Urquhart claims “shows promise as a strong and reversible underwater adhesive.”
“The team suggests it could have many applications that require controllable adhesion in aqueous environments,” Urquhart continued, adding that the team, led by Kimoon Kim, a professor at the university´s Department of Chemistry, was able to develop “a reversible and strong supramolecular adhesive that works underwater like the fabric hook and loop fasteners of velcro.”