Slug-inspired hydrogel adhesive – In the news

Sahana R from Nossal High School

Sticking a Band-Aid® on damp skin is not easy as we all know. There is a bigger challenge when a similar plaster is required to be used on internal parts of the body. The human body comprising 70% water, encloses the body’s tissues and organs and supports the regulation of various body functions. Therefore, a strong, biocompatible adhesive is essential to repair an open internal wound. Surgical glues are often used in the body instead of stitches, staples, and clips, to lower the risk of damage at the wound site. Using surgical glue also reduces cost and the patient’s time in hospital (Brownell, 2017). This means that the medical adhesive must be resistant to wet surfaces, be non-toxic and flexible to support tissue movements.

Source - Erik Veldhuis, modified by Tom Meijer (CC BY-SA 3.0)

The Dusky Arion Slug (Arion subfuscus) is a large species of slug found in North America and Western Europe. When threatened, the slug secretes orange-coloured mucus, covering the surface of its body. This mucus contains added proteins which sets it quickly, forming a sticky, elastic mass (Piazza, 2017). This mucus protects it from predators that attempt to prise it away, keeping it strongly adhered to the surface. This is due to the positively charged primary amine in the mucus and the negatively charged surface. (Bichell, 2017). The mucus proteins physically attach the slug to its surface by cross-linking with the surface proteins (Bichell, 2017). This tightly bonds the slug to its surface, even if the surface is very damp.

Jianyu Li, a former Post-doctoral Fellow, Wyss Institute at Harvard University, was inspired by this natural phenomenon of the slug to create an improved medical adhesive. With his team, Li created a double-layered hydrogel which contained similar positively charged proteins as the slug mucus. Previous designs of medical adhesives looked only at the interfaces of the tissue and adhesive, while the hydrogel design dissipates charges. These positive charges attract to negatively charged tissues, creating a strong bond between both the surfaces. During experiments, more than three times the energy was needed to break the tough bond compared with other adhesives (Mooney et al, 2017).

The hydrogel adhesive, when tested on both dry and wet pig tissues including skin, liver and cartilage, bonded stronger than other adhesives. When implanted in rats for two weeks, it caused no tissue damage and adhesion to other nearby tissues (Collins et al, 2017). However, these side effects were present in the current medical adhesives. When tested on a hole in an automated beating pig heart, the hydrogel adhesive remained bound and stable. These properties of hydrogel open up many opportunities in the medical field – the adhesive can safely be used as a patch, or as liquid glue for deeper wounds. This biodegradable material decomposes after the wound is healed (Brownell, 2017).

The hydrogel has the potential to help both surgeons and patients with its quick application and non-toxicity. Its ability to biodegrade makes it an environmentally better option and can be accessed by people in low socioeconomic status due to its simple construction. As more advanced technology emerges, I hope to see the hydrogel design develop and benefit patients in the future.

Reference List:

Bichell, R. G. (2017). Slug slime inspired scientists to invent sticky surgical glue. Retrieved 14 June 2020. https://www.npr.org/sections/health-shots/2017/07/27/539473673/slug-slime-inspires-scientists-to-invent-sticky-surgical-glue

Brownell, L. (2017). Sticky when wet: strong adhesive for wound healing. Retrieved 14 June 2020. https://wyss.harvard.edu/news/sticky-when-wet-strong-adhesives-for-wound-healing/

Collins, T., Fernandez, C. (2017). Slime from the common garden slug inspires a new ‘sticky plaster’ that helps internal wounds heal. Daily Mail. Retrieved 14 June 2020. https://www.dailymail.co.uk/sciencetech/article-4736224/Medical-bio-glue-developed-based-slug-secretions.html

Piazza, G. (2017). Medical glue inspired by sticky slug mucus. Retrieved 14 June 2020. https://www.nih.gov/news-events/nih-research-matters/medical-glue-inspired-sticky-slug-mucus

Mooney, D. J. et al (2017). Tough gel adhesives for wound healing. Wyss Institute. Retrieved 14 June 2020. https://wyss.harvard.edu/technology/tough-gel-adhesives-for-wound-healing/

The article above is one of the winning entries of GTAC's Biomimicry Blog competition. The competition challenged Victorian students to submit a blog article detailing an example of scientific and mathematical advances that were inspired by nature. Click here for more information.