Tag Archives: adhesives

English ivy’s stickiness may be useful

Researchers have discovered the secret to English ivy’s stickiness and they hope that secret will lead to improved wound healing and more according to a May 24, 2016 news item on Nanowerk,

English ivy’s natural glue might hold the key to new approaches to wound healing, stronger armor for the military and maybe even cosmetics with better staying power.

New research from The Ohio State University illuminates the tiny particles responsible for ivy’s ability to latch on so tight to trees and buildings that it can withstand hurricanes and tornadoes. (Not to mention infuriate those trying to rid their homes of the vigorous green climber.)

The researchers pinpointed the spherical particles within English ivy’s adhesive and identified the primary protein within them.

A May 23, 2016 Ohio State University news release (also on EurekAlert) by Misti Crane, which originated the news item, expands on the theme,

“By understanding the proteins that give rise to ivy’s strength, we can give rise to approaches to engineer new bio-inspired adhesives for medical and industry products,” said Mingjun Zhang, the biomedical engineering professor who led the work.

“It’s a milestone to resolve this mystery. We now know the secret of this adhesive and the underlying molecular mechanism,” said Zhang, who focuses his work on finding answers in nature for vexing problems in medicine.

“Ivy has these very tiny hairy structures that have a wonderful interaction with the surface as the plant climbs. One day I was looking at the ivy in the backyard and I was amazed at the force,” Zhang said.Like many scientists before him, Charles Darwin among them, Zhang found himself captivated by English ivy – the physics of it, the sheer strength of it. The study appears today in the journal Proceedings of the National Academy of Sciences.

“It’s very difficult to tear down, even in a natural disaster. It’s one of the strongest adhesive forces in nature.”

When he and his team took a look at the ivy’s glue with a powerful atomic-force microscope, they were able to identify a previously unknown element in its adhesive.

Zhang said particles rich in those proteins have exceptional adhesive abilities – abilities that could be used to the advantage of many, from biomedical engineers to paint makers.The tiny particles inside the glue on their laboratory slides turned out to be primarily made up of arabinogalactan proteins. And when the scientists investigated further, they discovered that the driving force behind the curing of the glue was a calcium-mediated interaction between the proteins and pectin in the gelatinous liquid that oozes from ivy as it climbs.

Zhang, a member of Ohio State’s Davis Heart and Lung Research Institute, is particularly interested in bioadhesives that could aid in wound healing after injury or surgeries. Others, notably the U.S. military, are interested in surface-coating applications for purposes that include strengthening armor systems, he said.

Many plants are excellent climbers, but scientists have had limited information about the adhesives that enable those plants to affix themselves to walls, fences and just about anything in their way, he said.

“When climbing, ivy secretes these tiny nanoparticles which make initial surface contact. Due to their high uniformity and low viscosity, they can attach to large areas on various surfaces,” Zhang said.

After the water evaporates, a chemical bond forms, Zhang said.

“It’s really a nature-made amazing mechanism for high-strength adhesion,” he said.

The glue doesn’t just sit on the surface of the object that the ivy is clinging to, he said. It finds its way into openings invisible to the naked eye, further solidifying its bond.

To confirm what they found, Zhang and his collaborators used the nanoparticles to reconstruct a simple glue that mimics ivy adhesive. Advanced bioadhesives based on this research will take more time and research.

In addition to its strength, ivy adhesive has other properties that make it appealing to scientists looking for answers to engineering quandaries, Zhang said.

“Under moisture or high or low temperatures, it’s not easily damaged,” he said. “Ivy is very resistant to various environmental conditions, which makes the adhesive a particularly interesting candidate for the development of armor coatings.”

Ivy also is considered a pest because it can be destructive to buildings and bridges. Knowing what’s at the heart of its sticking ability could help scientists unearth approaches to resist the plant, Zhang said.

Zhang and his work have been featured here before in a Jan. 7, 2013 posting about flesh-eating fungus and in a July 22, 2010 posting about English ivy and sunscreens.

Here’s a link to and a citation for Zhang’s latest paper,

Nanospherical arabinogalactan proteins are a key component of the high-strength adhesive secreted by English ivy by Yujian Huang, Yongzhong Wang, Li Tan, Leming Sun, Jennifer Petrosino, Mei-Zhen Cui, Feng Hao, and Mingjun Zhang. PNAS [Proceedings of the National Academy of Sciences] 2016 doi: 10.1073/pnas.1600406113 Published ahead of print May 23, 2016,

This paper is behind a paywall.

Opposite world: developing anti-adhesion surfaces

The power of the metaphor/analogy is demonstrated in a Sept. 24, 2013 news item on ScienceDaily where they’ve mentioned insects in the context of anti-adhesion—the opposite of how insects are usually referenced, i.e., how well they stick to surfaces and the search for better adhesives. Or you could put it down to lazy reading on my part as it took me a minute or so to make sense of what I was reading (from the news item),

Beetles, cockroaches, and ants will have a harder time walking up the sides of buildings or air conditioners in the future — thanks to the bio-inspired, anti-adhesive surfaces Prof. Dr. Thomas Speck, Dr. Bettina Prüm, and Dr. Holger Bohn are developing together with the Plant Biomechanics Group of the University of Freiburg. The team studied plant surfaces in order to determine what influence cell form and microstructure as well as surface chemistry exert on the adhesion behavior of insects.

The Sept. 24, 2013 University of Freiburg (Germany) press release,which originated the news item, describes the research and the new anti-adhesive surface in more detail,

The researchers conducted adhesion experiments in which Colorado potato beetles walked across differently structured plant surfaces as well as replicas made of synthetic resins. The team used a highly sensitive sensor to measure the traction forces of the beetles on various surfaces. They discovered that wavy or strongly curved cells can increase the adhesive powers of beetles, whereas microstructures composed of wax crystals or cuticular folds reduce them. The latter are tiny folds in the cuticle, a protective layer on the surface of the leaf resembling polyester. The beetles had the hardest time walking on surfaces with cuticular folds with a height and width of approximately 0.5 micrometers and a spacing of between 0.5 and 1.5 micrometers. “That is the perfect anti-adhesion surface. The insects slip off of it much easier than off glass,” says project director Thomas Speck. The cuticular folds reduce the contact area between the adhesive hairs on the beetles’ legs and the plant surface. Unlike on more coarsely structured surfaces, the beetle can’t dig its feet firmly into the cuticular folds. Thus, the microstructure of the surface has a stronger effect on the adhesion of the beetle than the cell form.

The team also took contact angle measurements to investigate the wettability of the various surfaces. The researchers used hydrophobic and hydrophilic artificial moldings of the microstructured plant surfaces in order to study the influence of the surface chemistry on surface wettability and the beetles’ walking behavior. Much like wax crystals, cuticular folds are very good at repelling water. In contrast to the wettability, which depends on both the microstructure and the surface chemistry, the walking behavior of the beetles is not influenced by the surface chemistry. This means that the beetle’s adhesive power depends solely on the physical microstructure of the surface.

Here’s a link to and a citation for the researchers’ paper,

Plant surfaces with cuticular folds and their replicas: Influence of microstructuring and surface chemistry on the attachment of a leaf beetle by Bettina Prüm, Holger Florian Bohn, Robin Seidel, Stephan Rubach, and Thomas Speck. Acta Biomaterialia Volume 9, Issue 5, May 2013, Pages 6360–6368

This paper is behind a paywall.