Slug Slime Inspires Super-Sticky Surgical Sealant

Wyss Institute at Harvard University
Wyss Institute at Harvard University

Some damp things, like sweaty thighs, only want to stick together. Others, like wet organs, are far less cooperative. But now scientists have devised a clever way to make them play nice: a two-part glue inspired by slug mucus. The team reported their results in the journal Science.

Surgical adhesive has a big job. It has to be safe, and it has to be able to stick to living tissue, even when that tissue is slick and wet with blood. So far, engineers have had a hard time finding glues that meet all these criteria.

That may be because, previously, they hadn't spent enough time lying on their bellies in the backyard. Ordinary slug mucus is a marvel of chemistry and physics. It's a liquid crystal, neither liquid nor solid. It protects the slug from pathogens, helps it glide along the ground, and can give off chemical messages to other slugs nearby.

And that's just the basic package. Individual slug species also brew special slime blends to suit their own needs. One European species, the dusky arion (Arion subfuscus), copes with threats by mucus-gluing itself to a surface and simply refusing to budge. Its slime is absorbent, strong, and super-sticky. In short, it's a surgeon's dream.

Previous studies of A. subfuscus mucus found that the slime derives its power from its unusual, two-layered structure, with a tough matrix covered with positively charged proteins.

To recreate this magical goo, experts in bio-engineering teamed up with material scientists and heart surgeons. They created their own version of the slime: a rugged hydrogel matrix beneath a sticky layer of large, positively charged molecules.

The researchers put the new glue through an impressive battery of product tests, trying it out on wet and dry pig parts, including skin, cartilage, hearts, arteries, and livers. They used it in rats that had recently undergone surgery, on mice with liver hemorrhages, and on pig hearts. In each case, the glue outperformed existing medical adhesives while causing no damage to surrounding tissue.

In a statement, co-author Adam Celiz, now at Imperial College London, said the slug glue has "wide-ranging applications."

"We can make these adhesives out of biodegradable materials, so they decompose once they've served their purpose. We could even combine this technology with soft robotics to make sticky robots, or with pharmaceuticals to make a new vehicle for drug delivery."

Donald Ingber is founding director of Harvard's Wyss Institute for Biologically Inspired Engineering, where some of the study researchers are based. He was not involved with this study, but praised the team for their ingenuity: "Nature has frequently already found elegant solutions to common problems; it's a matter of knowing where to look and recognizing a good idea when you see one."

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What Really Happens When Food Goes Down the 'Wrong Pipe'?

The dreaded 'wrong pipe' calamity can strike at any time.
The dreaded 'wrong pipe' calamity can strike at any time.
Photo by Adrienn from Pexels

Your average person isn’t expected to be well-versed in the linguistics of human anatomy, which is how we wind up with guns for biceps and noggins for heads. So when swallowing something is followed by throat irritation or coughing, the fleeting bit of discomfort is often described as food “going down the wrong pipe.” But what’s actually happening?

When food is consumed, HuffPost reports, more than 30 muscles activate to facilitate chewing and swallowing. When the food is ready to leave your tongue and head down to your stomach, it’s poised near the ends of two "pipes," the esophagus and the trachea. You want the food to take the esophageal route, which leads to the stomach. Your body knows this, which is why the voice box and epiglottis shift to close off the trachea, the “wrong pipe” of ingestion.

Since we don’t typically hold our breath when we eat, food can occasionally take a wrong turn into the trachea, an unpleasant scenario known as aspiration, which triggers an adrenaline response and provokes coughing and discomfort. Dislodging the food usually eases the sensation, but if it’s enough to become stuck, you have an obstructed airway and can now be officially said to be choking.

The “wrong pipe” can also be a result of eating while tired or otherwise distracted or the result of a mechanical problem owing to illness or injury.

You might also notice that this happens more often with liquids. A sip of water may provoke a coughing attack. That’s because liquids move much more quickly, giving the body less time to react.

In extreme cases, food or liquids headed in the “wrong” direction can wind up in the lungs and cause pneumonia. Fortunately, that’s uncommon, and coughing tends to get the food moving back into the esophagus.

The best way to minimize the chances of getting food stuck is to avoid talking with your mouth full—yes, your parents were right—and thoroughly chew sensible portions.

If you experience repeated bouts of aspiration, it’s possible an underlying swallowing disorder or neurological problem is to blame. An X-ray or other tests can help diagnose the issue.

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