Nanogirl Michelle Dickinson: The lifesaving powers of slug slime

The slime of a slug has amazing bonding abilities.

Wet winter days mean slugs and snails are commonplace in our gardens and flowerpots, leaving their sparkling silver trails, damaged plants and angry gardeners as evidence of their visit.

A team of scientists at Harvard University studying the creatures however may have made a medical breakthrough - a remarkable new adhesive mimicking the make-up of slug slime.

The mucus that slugs leave behind acts as a lubricant to help them move around, and serves as a messaging tool to point other slugs in the direction of a mate or food source.

The mucus is also what gives slugs and snails their unique ability to stick to surfaces, even if the surfaces are wet.

One type of slug, the Dusky Arion (Arion subfuscus), is able to secrete mucus so strong when threatened by a predator that the slug cannot be pried off the surface. Although it has the sticking power of superglue, the mucus is still flexible enough to allow the slug to bend without detaching.

It is this combination of flexibility and super-stickiness on wet surfaces that caught the scientists' attention when they were looking for a new way to stick wounds together.

Anyone who has tried to put a plaster on wet skin knows how hard and usually unsuccessful the task is - wet surfaces are one of the biggest challenges for biological glues. These challenges multiply when working inside the body, with the need to adhere to flexible tissues and moving organs while being immersed in body fluids.

Current commercial glues become stiff when they dry, are toxic to cells and do not bond well in wet environments. As a result of these limitations, most internal wounds have to be physically stitched or stapled back together. A new gel patch, based on the study of slug slime, may change that.

The researchers found the slime's amazing bonding abilities come from three separate mechanisms. The first involves electrostatic attraction, where opposing electric charges on surfaces bond to one another.

The second involves covalent bonding between the atoms on the surface of the material to the atoms in the slime.

The third mechanism uses the long proteins in the slime to intertwine with the surface molecules in a way that creates a tangled and strong physical bond.

Rather than use the slime of actual slugs, the researchers found an algae that produced a similar chemical and combined it with water to form a gel patch. The patch was used to add flexibility to the adhesive, allowing it to dissipate movement energy without breaking the bonds with the surface.

Their final patch is as sticky as super glue, non-toxic, and sticks to wet surfaces while also being flexible enough to tolerate the movement of working organs like the heart and lungs.

So far the patch has been successfully used in animal experiments - for instance patches were stuck to a pig's beating heart and subjected to tens of thousands of cycles of stretching, and used to stop haemorrhaging from holes in the livers of mice. Not only was it successful, it remained sticky for the duration of the two-week experiment, giving the body enough time to start healing itself.

With many potential applications in the medical fields - a patch applied to tissue surfaces, an injectable solution for deeper injuries or a tape that attaches medical devices, the sticky gel could solve many medical problems.

Though it will take a while to be approved for human use, the next time you head out and see a revolting, slimy slug eating your winter vegetables, just remember, one day they could save your life.