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An interdisciplinary team of McGill researchers has developed an ultra-strong, environmentally friendly medical glue, or bioadhesive, made from marine waste. The discovery has promising applications for wound care, surgeries, improved drug delivery, wearable devices and medical implants.

"Being able to produce glues that can close wounds or make something strongly adhere to the skin is critical for many medical interventions," said Audrey Moores, Professor in the Department of Chemistry.

"Many existing bioadhesive products are based on toxic compounds, while overall, there is a need to explore new materials that demonstrate both high adhesion and strong fatigue resistance, or the ability to hold even if pulled apart repeatedly," Moores said.

Moore and main co-author Jianyu Li, Associate Professor, Department of Mechanical Engineering and Canada Research Chair in Tissue Repair and Regeneration reported their findings in "Nanowhisker glues for fatigue-resistant bioadhesion and interfacial functionalization," in Nature Communications.

Naturally sourced nanowhiskers give the glue its strength

The new bioadhesive is composed of chitosan, a chemically modified form of chitin, the natural building block found in the exoskeletons of shellfish and certain fungi.

The researchers modified the chitosan to have a nanowhisker shape—a feature that proved to be essential to the bioadhesive's effectiveness—using a mechanochemical process pioneered by co-authors Moores and Edmond Lam in previous studies.

"We chemically manipulate this material to turn it into nanochitosan, which has a range of different properties we can finetune. Using this nanomaterial, we can make nanoglue," Moores said.

Ultrasound turns whiskers into interlocking structures

To apply the nanoglue, researchers use a unique ultrasound technology developed by the Li group to penetrate the skin. When exposed to sound waves, the nanowhiskers not only adhere firmly to skin but also interlock into a rigid, resilient scaffolding that drastically enhances the glue's strength and durability.

"Imagine you have a Band-Aid on your hand. It's difficult to get it to stay, because your hand moves a lot," Moores explained.

"To get it to stick, you need the skin to be permeable to the glue. We used microneedles or ultrasound for that.

"We were surprised to see that ultrasound was critical to making a strong glue. While our initial strategy was to get the nanoglue to stick to the skin, we also discovered ultrasounds helped build a complex, interconnected network of our nanostructures. These nanowhisker glues are simply better than the current glues out there."

They say the nanostructure has promising applications beyond health care, in many engineering contexts.

Allergy-safe, and potentially vegan

The bioadhesive is also fully biocompatible, even for people with seafood allergies.

"People who are allergic to shellfish are not allergic to chitin, but the proteins. We can remove these in the manufacturing process and avoid allergic reactions.

"We could also theoretically make a vegan version from fungi," Moores added.