Love among the cicadas provides new way to fight antibiotic immune killers

Many Australians are sentimental about cicadas. Trading a rare black prince at school. Collecting the exoskeleton of a green grocer. The threat of an angry brother with a pisswhacker in hand.

But it was the discovery that cicadas' fairy-like wings had nearly magical powers to withstand bacteria that has fascinated a husband and wife team of Australian nanoscientists, doctors Gregory and Jolanta Watson.

These qualities are giving hope to medical scientists around the world looking for a way to defeat the antibiotic-resistant bacteria that kills tens of thousands of people every year.

"It is killing bacteria not with chemistry but with a physical means," Dr Gregory Watson said of cicada wings.

It was against the "deafening sound" of cicadas chirping early summer nearly 20 years ago that the couple - who share a birthday and many interests - went from "hate at first sight" to a partnership in the lab and then at home.

Together they have helped put Australia at the forefront of research using the unique properties of cicadas to fight antibiotic-resistant bacteria.

"We would walk around the campus, and pick up anything that looked interesting and put it under the microscope," Greg said. They were often "rained upon from above" by cicadas.

"We'd often just find a wing, and we'd think the microbes and the environmental attack is much stronger on the body. If the wings are still intact, they must have some microbial resistance," he said.

Under an atomic-force microscope, which can view tiny topographies??? only a few atoms in height, the scientists now at the University of the Sunshine Coast made some surprising discoveries.

The couple weren't the first to discover the wings were non-reflective, but they became fascinated with why. This led them to discover the wings' structure made them resistant to bacteria and other contaminants.

They experimented with liquids, solids, contaminants and pollens to see how the wings cleaned themselves.

"Cicadas have different bumps, some have big bumps, some have little bumps [including the common green grocer]," they said.

Their current research concludes the width of each of the nanoparticles or nano spikes, and the size of the space between them, is key to how they resist bacteria. Each spike is about one thousandth of the thickness of a human hair.

When Professor Elena Ivanova???, a scientist in Victoria who won this year's Eureka Prize, was looking for information on antibacterial surfaces, she wrote to the Watsons. They provided her with their wing samples.

In the lab pathogen Pseudomonas aeruginosa settle on the wings, but within three minutesare dead.

"Under the microscope, the nanoscale pillars of the cicada wing seem to have punctured the cell walls of the bacteria, causing their innards to spill out and leading to a quick death," reported American network PBS who recently documented this research.

"Ivanova and her colleagues added a couple of fluorescent dyes to the wing's surface that bind to the DNA inside bacteria, glowing red in those that have punctured membranes and green in those that are healthy. Under their bench-top microscope, the surface looked like a bloody battle had just taken place," said PBS's Alex Riley.

It was the first reported example of a naturally existing surface with a physical structure that exhibits such effective bactericidal properties," a paper by the Watsons with Professor Ivanova in 2013 said. "The nanopattern on the surface of Clanger cicada (Psaltoda claripennis) wings represents the first example of a new class of biomaterials that can kill bacteria on contact based solely on its physical surface structure," they said.

Only last month Professor Ivanova and Professor Saulius Juodkazis won the prestigious 2017 UNSW Eureka Prize for Scientific Research. They replicated these surface patterns on a nanomaterial constructed out of metallic materials with tiny self-sterilising protrusions.

They are now working with an implant manufacturer in the hope of engineering an anti-microbial nanosurface onto artificial joints to prevent infections they say affect millions. They also plan to fabricate nanostructures based on the cicada and dragonfly (which has similar properties) on non-metallic surfaces such as plastic, ceramics, glass and silicon. These could be used for anything from pathogen-proof paint to infection-resistant water filtration systems.

The Watsons, too, are aflutter with ideas - they are just completing a paper that suggests uses for cicada wings from micro-ribbons that clean the bloodstream to cleaning water in the middle of Africa.

"It is only limited by your imagination," said Jolanta.

???"There is still so much we don't understand and don't know, " she said, adding that she encourages her students to play and experiment.

"If we hadn't gone and said 'Why is the body dead and disintegrated and the wing still intact?' we wouldn't have progressed."

Now when the cicadas come out, they encourage people to stop.

"Hear that noise!! Be a little more appreciative of nature and what nature can do for us. It is very kind to us in many ways," she said.


This story Love among the cicadas provides new way to fight antibiotic immune killers first appeared on The Sydney Morning Herald.