Mussels provide muscle for new adhesive.

• Position: Chemistry

Mussels are true masters of adhesion. They bond solidly underwater to nearly any type of surface. Researchers have been inspired by mussel adhesive proteins to add another exciting property. As they report in the journal Angewandte Chemie, their new adhesive can be debonded on demand.

Glue previously was considered to be a cheap and flimsy solution. However, modern adhesives are very high-tech. For example, they can hold together the aerofoils of airplanes. However, three items persist on the wish lists of adhesion scientists: reliable bonding underwater for fixing teaks in pipelines or sealing bleeding wounds during operations: "self-healing" adhesives that would prevent catastrophic failure: and adhesives that can be debonded "on demand" with no residue for easy replacement of components or dismantling composites for recycling.

In nature there are astonishingly robust, strongly bonding, universal adhesives that meet the first two requirements: mussels use them to stick to nearly all types of surfaces, from rocks to wooden posts to the metal hulls of ships. The amino acid dihydroxyphenylalanine (DOPA) is critical to this amazing adhesive effect. The DOPA groups contained in the adhesive react stepwise under the conditions prevalent in seawater to form a crosslinked polymer matrix capable of bonding to inorganic oxides in rock. They also bind to polyvalent metal ions, such as iron...