When the Dusky Arion slug (Arion subfuscus) feels threatened, it secretes a mucus that makes it almost impossible to remove from whatever surface it happens to be on. Inspired by that stick-to-it-iveness, Harvard scientists led by Dr. Jianyu Li have created an adhesive gel that could conceivably be used in the human body, to close up surgical wounds or secure implants in place.

Modelled after the natural slug slime, the new "tough adhesive" is a hydrogel (a gel in which the liquid component is water), and it has two layers: a strong yet flexible inner matrix, and an exterior adhesive layer with positively-charged polymers protruding from it.

When the gel is applied to a surface – even one that's wet with blood or other fluids – those polymers readily adhere to it. This is due to three factors, including covalent bonding, which involves the sharing of electron pairs between neighboring atoms; electrostatic attraction of the polymers to negatively-charged cell surfaces; and physical interpenetration, which is the gel's ability to seep into all of the surface's nooks and crannies.

The tough adhesive can be formed into either sheets (teal blue) or custom shapes (dark blue)(Credit: Wyss Institute at Harvard University)

In lab tests, the gel has successfully been adhered to both dry and wet pig skin, cartilage, heart, artery, and liver tissue. It has even been used to seal a defect in a pig heart that was slick with blood – the seal didn't leak, even when the heart was inflated. Additionally, it has been used to stop sudden blood loss in rats, performing comparably to a hemostat, which is commonly used in emergency situations to stem bleeding.

What's more, the gel is also completely non-toxic and biocompatible, not harming human cells – the same can't be said for some of the surgical superglues currently used to close up incisions or lacerations.

A paper on the research was recently published in the journal Science.

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