When working with wet surfaces on biological tissues, such as during surgery, a simple bandage just won’t stick. After receiving a spark of inspiration from slug goo, however, scientists now think they’ve got the solution.
Researchers from the Wyss Institute for Biologically Inspired Engineering at Harvard University have created a super-strength adhesive material that is able to bind to biological tissues even when wet, without causing toxicity. Their research is published in this week’s issue of the journal Science.
Dusky Arion slugs (Arion subfuscus) were the muse for this breakthrough. This innocent species of slug, found across Europe, Asia, and parts of the US, secretes a mucus that is able to bind to surfaces. Even if the surface is coated in water, the slug is able to remain “glued” there, should a predator attempt to peel it off. The scientists on this project looked at the properties of this slug goo to uncover how it sticks so successfully.
“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," Donald Ingber, founding director of Wyss Institute and Professor of Vascular Biology at Harvard Medical School, said in a statement. "We are excited to see how this technology, inspired by a humble slug, might develop into a new technology for surgical repair and wound healing."
Just like the slug mucus, their design uses three mechanisms: electrostatic attraction to negatively charged cell surfaces, covalent bonds between neighboring atoms, and physical interpenetration. This new material is also topped with a special matrix that has positively-charged polymers poking out from its surface.
"Most prior material designs have focused only on the interface between the tissue and the adhesive,"added first author Jianyu Li. "Our adhesive is able to dissipate energy through its matrix layer, which enables it to deform much more before it breaks."
Experimental tests showed that the material stuck to dry and wet pig tissues – including skin, cartilage, heart, artery, and liver – with almost three times greater strength than other medical adhesives. Unlike many current medical adhesives, the material can also be formed into custom shapes.
"This family of tough adhesives has wide-ranging applications," says co-author Adam Celiz, currently of Imperial College London. "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."