That was almost nine years ago. Today, Zhang and a team of biomedical engineers at Ohio State University are leading the research behind ivy’s glue-like secretions and say the implications hold promise for medical and military advances.
The source of ivy’s unmatched adhesive abilities — a mystery that scientists such as Charles Darwin have pondered for more than a century — lies at the nanoscale.
Ivy roots are made up of nanoparticles — tiny particles that Zhang described as 1 million times smaller than the width of a human hair. These nanoparticles have bends, bumps and holes on their surfaces but are otherwise uniform in structure.
When millions of them combine, they become highly compact and fit together like a jigsaw puzzle. This is how ivy can cling to almost any surface with a force 1.8 million times its own weight, Zhang said.
“It is one of the largest forces in nature,” he said.
The team has identified not only the nanoparticles that comprise ivy’s sticky secretion, but the protein it contains. It’s called arabinogalactan, and it reacts with other chemical and physical elements in the plant to produce the gluey secretion.
The more they understand how it works, the easier it will be to create biomedical applications, Zhang said. They could include scarless tissue repair or tissue engineering.
“This is something particularly promising,” he said.
Zhang also works with researchers at the OSU Davis Heart and Lung Research Institute. Because of this connection, the team plans to look specifically at treatment possibilities for cardiac diseases, such as congestive heart failure, said Yujian Huang, one of Zhang’s doctoral students.
“It’s interesting, but also important,” Huang said.
The team also is looking at ways to develop water-resistant, environmentally sustainable military coatings for such things as submarines, Huang said.
Zhang said while there are other plants with similar protein secretions, none seem to compare to the strength of English ivy.
“Ivy is the only one we found that has the most uniform nanoparticles secreted from the plant,” he said. “That’s why ivy generates such stronger forces.”
Zhang’s research is one of the latest in the field of biomimetics, which translates to “mimicry of life.” Biomimetic scientists study and then try to imitate natural processes. They include super sticky gecko feet and lotus leaves, which repel water.
“This field (of biomimetics) is one that people are becoming very excited about,” said Hillel Chiel, a professor of biology at Case Western Reserve University. “Each time you get an idea from nature, you can use that as a novel design, and in many cases those are more robust and effective than the artificial ones.”
Chiel said that as this field grows and new ideas emerge, people are realizing there is still a lot to learn from nature. Chiel said the OSU ivy research sounds interesting.
“Novel adhesives could have massive applications, like wound healing,” he said. “It looks very, very promising.”
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