Fly fishermen refer to them as "rock rollers" and use them for bait. For the uninitiated, caddisflies are alien-looking bugs related to butterflies and moths that spin silk that stays sticky underwater. Now University of Utah researchers are beginning to unlock their mysteries and hope to enlist caddisfly larva in the development of new adhesive tape that can be used during surgery, according to Science Daily.
"I picture it as sort of a wet Band-Aid, maybe used internally in surgery — like using a piece of tape to close an incision as opposed to sutures," said Russell Stewart, associate professor of bioengineering at the University of Utah and principal author of the new caddisfly study. "Gluing things together underwater is not easy. Have you ever tried to put a Band-Aid on in the shower? This insect has been doing this for 150 million to 200 million years."
Caddisflies make up an order of insects that live around the world in waters ranging from fast streams to quiet marshes. They share an ancestry with other creatures that spin dry silk during their larval stages, including butterflies and moths, but unlike their land-dwelling cousins, caddisfly larva have evolved to spin their silk while underwater. Some species use their amazing waterproof silk to build casing which they drag along with them underwater while foraging for food; others are known to glue themselves to rocks and catch passing food with a silk net.
"There's just a fascinating diversity of these insects. Their adhesive is able to bond to a wide range of surfaces underwater: soft and hard, organic and inorganic. If we could copy this adhesive it would be useful on a wide range of tissue types," added Stewart.
Stewart and his fellow researchers analyzed caddisfly silk using several methods, including scanning electron microscopy. It is an intricately woven fiber made of large proteins named fibroin with an amino acid named serine. The caddisfly silk appears to get its underwater adhesive abilities from serines that have phosphates added to them as the fibroin silk protein is synthesized. Phosphates are well-known adhesives that are already used in everything from dental crowns or fillings to water-based latex paints.
The silk's most practical use would likely come for surgeons as a replacement for sutures, since until now a tape made from a bioadhesive would have been impossible to use due to its inability to stick to wet tissue. Caddisfly-inspired tape could offer surgeons a far simpler, more efficient and flexible way to join body tissues together than modern sutures provide, since sutures need to be woven using needle and thread.
"You wouldn't be able to make shirts out of it, but you might be able to make wet Band-Aids," said Stewart.
Swimsuits made from the material would also be ill-advised — that is, provided caddisfly larval casings don't become the latest swimwear fashion trend.