Shellfish-inspired glue sticks even in water

Inspired by shellfish such as mussels and barnacles that secrete very sticky proteins that help them cling to rocks or ship hulls, even underwater, researchers have designed a material to create a waterproof adhesive.

Application of the biologically-inspired glue could be found in repairing ships, helping heal wounds and in surgical incisions.

"They are the strongest biologically inspired, protein-based underwater adhesives reported to date," the researchers said.

To create the new material, the researchers at the Massachusetts Institute of Technology in the US engineered bacteria to produce a hybrid material that incorporates naturally sticky mussel proteins as well as a bacterial protein found in biofilms - slimy layers formed by bacteria growing on a surface.

When combined, these proteins form even stronger underwater adhesives than those secreted by mussels, the findings showed.

"A lot of underwater organisms need to be able to stick to things, so they make all sorts of different types of adhesives that you might be able to borrow from," said senior author Timothy Lu.

The sticky substance that helps mussels attach to underwater surfaces is made of several proteins known as mussel foot proteins.

In the study, the researchers wanted to engineer bacteria to produce two different foot proteins, combined with bacterial proteins called curli fibres - fibrous proteins that can clump together and assemble themselves into much larger and more complex meshes.

They engineered bacteria so they would produce proteins consisting of curli fibres bonded to either mussel foot protein 3 or mussel foot protein 5.

After purifying these proteins from the bacteria, the researchers let them incubate and form dense, fibrous meshes.

The resulting material has a regular yet flexible structure that binds strongly to both dry and wet surfaces.

The study appeared in the journal Nature Nanotechnology.