UC Santa Barbara scientists have replicated the uncanny underwater adhesive capacity of mussels – which has previously inspired a surgical glue – in a versatile and strong synthetic material. The ultra-thin material boasts up to 10 times the effectiveness of prior wet/underwater adhesives, and its low molecular weight and functional properties means that it can be used to boost the performance of existing bulk adhesives, as well as in such varied applications as dentistry, nanofabrication, and underwater repair.

Mussels are able to cling to rocks and other surfaces through wind and crashing waves thanks to proteins that they secrete through their feet in the form of byssus threads (silky, strong, fine fibers). The researchers knew from decades of research into the mechanics of this tethering process that there are certain key molecular groups in the adhesion proteins.

Specifically, some of the proteins are rich in the amino acid L-Dopa, which is known to provide underwater adhesion and self-healing capabilities. These properties rely on a hydrogen-bonding compound called catechol, which keeps the threads from sticking to water.

The researchers designed a molecule that mimics these proteins to form ultra-thin glue layers that are able to fuse two surfaces underwater. Their adhesive primer is subject to three pending patents, and will be further developed by a spinoff venture called NanoM Technologies, LLC.

In addition to priming or sticking surfaces that are regularly exposed to the elements, the team says the adhesive also has potential in the field of electronics. This is due to the small molecules of the material forming atomically smooth, ultra-thin layers that could be used in the fabrication electronic circuits and battery components.

Additionally, the bioinspired adhesive doesn't require the use of toxic chemicals, volatile organic solvents or the input of external energy such as heat or light, making it sustainable and environmentally friendly.

Mussels aren't the only sea creatures inspiring scientists in wet-adhesive research. Last year, researchers at Newcastle University uncovered the secrets to barnacle binding, while earlier this year a team from Nanyang Technological University developed a glue that sticks to wet surfaces when an electrical charge is applied.

This latest research into underwater glue is described in a paper published in the journal Nature Communications.

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