Imitating mussels to create strong hydrogels

MIT researchers have found a way to create strong, flexible threads by imitating the natural ability of mussels. During the 2019 Materials Research Society fall meeting, grad student Sean Cazzell presented his and Professor Niels Holten-Andersen's discovery.

Mussels are able to stick to rocks underwater through threads called byssal, which they generate through a breaking and re-forming process that is purely chemical. Strong hydrogels are formed when a metal atom binds to three polymer chains (these polymer chain and metal atom links are called cross-linked metal coordination bonds). Cazzell and Holten-Andersen found a way to create a self-healing hydrogel in a wider range of metal concentrations through the use of competition controlled by the pH, or acidity and alkalinity, of the environment. In their model computational system, Cazzell confirmed that in the absence of pH-managed competition, extra metal overwhelms the ability of the polymer to form sturdy cross-links. Under excess metal concentrations, strong triple cross-links are more likely to form. Their findings could potentially have use in advanced 3D printing of synthetic tissues and other biomedical applications.