These velvet worms squirt a jet of slime that is inspiring the development of biopolymers. | Image: Alexander Bär

Imagine a smart glue that knows when to set. This is how Yendry Corrales-Ureña and Fabienne Schwab described the properties of velvet-worm slime in a recent study.

At first glance, there is nothing very glamorous about it. To immobilise its victim, the velvet worm squirts it with a jet of slime, which increases in viscosity as soon as the insect moves in an attempt to escape. But for scientists working on the development of biopolymers, it has become a source of inspiration. Indeed, a fast-setting ‘smart’ biopolymer could have many applications, e.g., in surgery where it would close wounds in a more targeted way than biomedical adhesives, which must stick to soft tissue, even in moist environments.

In their search for the mechanisms causing the slime to set, the researchers discovered that this mucus contains carbonate and phosphate particles that break up when agitated quickly. “We had been investigating the phenomenon for weeks before realising that the key to this super glue lies in carbon dioxide”, says Schwab. “The carbonates and phosphates dissolve and react with each other in an acid-base reaction. As in the case of baking powder, the carbonate is decarboxylated and CO₂ released. This in turn greatly accelerates the drying of the mucus”.

According to Schwab, there is still a number of steps to be taken to develop biopolymers based on carbonates and phosphates that will function like the slime of the velvet worm. But there are also many other substances in the mucus whose role is not yet known. “To find out which particles are essential for a polymer to dry so quickly when subjected to movement, further studies are needed, including attempts to replicate mucus and its functionality in the laboratory”.

Y. Corrales-Ureña et al.: Encapsulated salts in velvet worm slime drive its hardening. Nature (2022)