Slug mucus: one day you might thank it for saving your life, thanks to a new class of gastropod-inspired adhesives that have the potential to transform centuries of surgical practice.
Intrigued by the strong and sticky defensive mucus exuded by a species of small brown slug called the Dusky Arion (Arion subfuscus), a team of researchers led by Jianyu Li, of Harvard University, created a new type of synthetic adhesive that, because it sticks to biological tissue, can be used to seal wounds.
The substance is important because existing glues perform poorly when used for wound healing. Superglues, which produce very strong bonds, are toxic. Other glue types, such as those comprising nanoparticles and a recently developed class of hydrogels inspired by natural sticky substances produced by mussels, form only weak bonds when used on wet and slippery surfaces.
By analysing the structure of slug goo, Li’s team made a tough adhesive that bonds tightly even on blood-slick tissue and is well tolerated by the immune system.
In a paper published in Science, the scientists report the new substance consists of two layers: an adhesive surface and a “dissipative matrix”, a stratum that varies in temperature, water content and stored energy.
The two layers work together to increase over-all bonding strength: the first by a mixture of “electrostatic interactions, covalent bonds, and physical interpenetration”; the second by slowing down the way the substance responds to stimuli (an effect known as “hysteresis”.)
Li’s team reports the new glue successfully bonds to pig skin, cartilage, heart, artery and liver tissue.
To test the strength of the substance, the researchers took a fresh pig’s heart, covered in blood, and glued a patch across a tear in one of the ventricles. They then pumped up the heart to full capacity, putting maximum strain on the adhesive, which held without difficulty.
They also simulated trauma wounds in rats and were able to successfully stem bleeding and reunite torn tissue.
The researchers suggest the work might form the basis for new products that will substantially change approaches to wound care and tissue repair.
“The mechanical performance and compatibility with cells and tissues,” they write, “allow these materials to meet key requirements for next-generation tissue adhesives.”