Slug Mucus Is So Sticky, It Inspired a New Kind of Surgical Glue

Slimy slugs, which use mucus to cling to even the most slippery surfaces, have inspired scientists make their own mucus for sticking human bodies back together.

By breaking down what allows the slug mucus to be so clingy, scientists were able to develop a new range of medical glues to be used in surgery and emergency care, according to a new study published Thursday in Science.

"We were trying to copy the key characteristics that biologists had discovered about these slugs," Jianyu Li, a bioengineering postdoctoral fellow at Harvard University, and lead author of the study, told me. "The results are very, very good."

Biomedical adhesives are used to bond tissue like organ defects or help wounds heal. A small gash can be dressed with an adhesive in lieu of stitches to help close the wound, for example. But Li told me there are some shortcomings with adhesives currently on the market, such as cyanoacrylates. These are often stiff, inflexible, and start to harden the moment they come into contact with moisture, including blood. Many are also toxic. This is obviously not ideal when trying to dress a wound or use an adhesive in surgery.

So Li and his team turned to nature to try to find a better way, specifically the Arion subfuscus slug. Subfusci are mostly found in Europe and Asia, in damp woodland areas like the underside of fallen trees. They're about two inches long, yellow, and covered in mucus, which allows them to cling to surfaces, even if those surfaces are wet.

Li told me the secret is that the mucus these slugs produce includes positively-charged calcium ions—which means it can use electrostatic energy to bind to surfaces. The researchers created a synthetic version of this adhesive and laid it on top of a hydrogel matrix to allow the glue to dry more slowly and stay malleable, even when wet.

"The combination of these two means the tissue environment has to put in more energy in order to break it down," Li said.

They tested the new adhesive on pig skin and hearts, including patching a defect in a pig heart. They then manually beat the pig heart to see how the patch held up, and saw that it stayed intact even at blood pressure levels of 367 millimeters of mercury (in comparison, normal human blood pressure ranges from 80 to 120 mmHg).

There's a growing demand for more advanced medical adhesives, so there's a good chance this new glue will eventually be used in regular rotation. And we can thank our slimy slug buddies for that.

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