Sticky Science
New Underwater Adhesives Inspired by Mussels
By Paul Erickson, COSMOS Science Contributor
Rich fragrances of herbs infused with the essence of the New England coast rise from our steaming dish of Sicilian blue mussels—a menu item that has lured my wife and I repeatedly to Cape Ann’s superb seafood restaurant Lobsta Land.
As it turns out, the same species of mouthwatering mussels we are devouring has inspired the formula for a remarkable adhesive that sticks to underwater surfaces. That is good news for divers attaching healthy lab-grown coral to damaged reefs—to mention one benefit the new adhesive provides.
Clever Clingons
The blue mussels, Mytilus edulis, range from the Arctic to South Carolina. In addition to Cape Ann’s rocky shores, mussels cling to boat hulls, ropes, metal pipes, wooden pilings, concrete piers, and each other.
How does this marine species conduct such sticky behavior? It uses a remarkable self-induced adhesion system which can be adapted to a wide variety of surfaces.
First, the mussel extends its muscular “foot” to a wet surface. From glands within the foot it secretes a footpad—a sticky, liquid blob. Then, while retracting the foot, the mussel spins a flexible byssus (sounds like BISS-us) thread. Both the footpad and the thread harden on contact with water.
By performing this crafty task over and over, multiple threads between mussels and various surfaces serve as strong-yet-flexible bungee cords, securing the bivalve under exploding waves and grinding sea ice. Now you know how mussels hang on, and why they might become an invasive problem.
Blue Mussels, Mytilus edulis, highly prized as food, Gulf of Maine. Photo © Andrew J. Martinez.
The Secret Sauce
DID YOU KNOW?
The process of copying nature’s ways to develop systems and materials beneficial to humanity has the scientific term of biomimicry or biomimetics. This field of science is becoming a rich source for manufactured innovation of technology and materials.
The catechols in mussel footpads and threads also contain the amino acid L-DOPA, which has been explored to treat Parkinson’s disease.
Despite appearances, mussels have only one external shell, consisting of two, hinged half shells or “valves.” Thus, the term “bivalve” mollusk.
To prevent mussels from sticking, people have applied toxic paint to boat hulls. Now scientists are experimenting with oil-infused silicone coatings to prevent the bivalves from getting a grip.
Inspired by his underwater observations of mussels, Purdue University professor and diver Jonathan Wilker set out to mimic and modify mussel adhesion chemistry.
After Wilker learned that mussel footpads consist of proteins containing adhesive molecules called catechols (sounds like CA-tuh-cul), he and his students developed lab-synthesized underwater adhesives by replacing the proteins with polystyrene catechol compounds.
Prototype to Product
Enter Mussel Polymers, a Bethlehem, Pennsylvania startup. They licensed the methods Wilker and his team engineered. Mussel Polymers now manufactures poly-catechol-styrene (PCS)—the strongest known commercial, underwater adhesive. The manufacturing process sacrifices no mussels for the new adhesive.
George Boyajian, CEO of Mussel Polymers, says the non-toxic, biodegradable PCS adhesive promises wide-ranging applications in dentistry, surgery, and underwater technology.
For more information about mussel glue check out www.musselpolymers.com, preferably while you are savoring a delicious dish of Sicilian mussels at, where else? Lobsta Land.