The lowly mussel inspires a revolutionary adhesive

Long before humans mastered fire and invented the wheel, mussels were manufacturing adhesives to securely fasten themselves to rocks amid ocean waves and tidal ebbs and flows. Now, well into the 21st century, the secrets of the mussel’s adhesive are finally being unraveled. A team of scientist led by Niels Holten-Andersen and Ka Yee Lee of the University of Chicago recently announced that they discovered how to synthesize the sticky substance mussels secrete.

The ability of mussels to stick to surfaces while underwater is simply astonishing. Nearly all commercial adhesives require surfaces to be clean and dry before application. Water has always been the bane of adhesives (just ask any angler trying to repair wading boots). By using chemistry to cross-link protein molecules, mussels bind to rough, slimy surfaces even underwater. After years of research, scientists are learning how to mimic the mussel.

The endeavor to reproduce techniques that nature already perfected is called biomimicry. Janine Benyus popularized the notion in her 1997 book Biomimicry: Innovation Inspired by Nature, and even devoted a section to the astounding properties of mussels. She notes that

We are flummoxed by the fact that crafty mussels are able to spread adhesive in the deep, cure it wet, and then count on it to stick to just about anything, all while surrounded by water.

This is what the team of researchers figured out. By building on recent advances that used atomic-force microscopy to puzzle out the mussel’s secrets, the researchers synthesized an organic polymer and mixed it with metal salts at low pH. The mixture turns into a gel when the pH is increased by adding sodium hydroxide. In addition to uses as an underwater adhesive, the substance has medical applications as surgical glue. And, because its design is based on nature, it can be manufactured in an environmentally friendly manner.

Since the time of Descartes, western civilization has striven to be “masters and possessors of nature.” Faced with environmental degradation and ecological collapse, we are now becoming victims of the Cartesian success. Biomimicry, which challenges scientists to learn from the natural world rather than master it, provides a sustainable approach to ensure the children of the children of today’s children can continue to contemplate the wonders of the mussel.