Frog Tongues May Be the Key to Stronger Adhesives [Study]

One waxy tree frog is licking another who looks surprised.

Nature has always played an important role in finding efficient solutions to problems that have long perplexed scientists and manufacturers alike, like wind and solar energy or biodegradable plastic alternatives.

Now, according to a new study, scientists have started to find new ways to make adhesives from frog saliva.

Most frog species naturally produce flame-retardant films bondable with a wide range of organic and inorganic materials. Long known for their sticky tongues, frogs have now caught the eye of the adhesive industry, who seek to incorporate frog saliva properties into their products.

Researcher Discovery Leads to Unexpected Applications

In November 2018, researchers at Oregon State University published a study describing how frog tongues manage to adhere to so many surfaces.... it turns out the secret was in their spit.

Two of the most common adhesive films are pressure-sensitive and heat-activated films. Pressure-sensitive adhesive films (PSAs) are mostly used in commercial and domestic scenarios while heat-activated adhesive films are frequently employed in industrial projects involving rubber and polymer-based materials.

Sticky frog mucus functions as a PSA; The frog’s tongue provides the necessary pressure for it to catch and trap prey.

Using Fibrils as “Molecular Shock Absorbers” to Create Bonds

According to Joe Baio, assistant professor of bioengineering at the Oregon State University College of Engineering, the study helped “determine the chemical structure of the surface of this mucus after a tongue strike, which had not been done previously.”

Watching frogs catch prey under a microscope led to the discovery of minuscule protein bonds, called fibrils, that form between the frog’s tongue and its target. Fibrils consist of multiple protein chains that twist around a central axis to form complex, durable bonds. When a frog strikes its prey, its saliva quickly forms fibrils with the target’s surface, and the tongue’s velocity ensures there is sufficient pressure to quickly form these fibrils.

According to Baio, fibrils allow the mucus to “generate strain-responsive adhesive forces by acting as molecular shock absorbers for the tongue.” Effectively, these protein structures create strong adhesive bonds at high speeds, allowing frogs to catch prey while they remain on the move.

Is Using Frog Spit Too Much of a Leap for Adhesive Manufacturers?

Biomimicry is far from a new concept in terms of how animals imitate other animals to achieve their own goals, and it turns out we may have a lot to learn from our green, sticky-tongued friends. Researchers are now looking for ways to simulate frogs’ ability to quickly form fibrils on almost any surface to better enhance industrial adhesives’ sticking capabilities.

Soon, synthetic and organic adhesive compounds may begin appearing for commercial use, resulting in cleaner, more efficient sticking solutions to reduce the environmental impacts of standard industrial adhesives.

Image Credit: Cathy Keifer /

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