Bacteria-shredding insect wings inspire new antibacterial packaging

The nanotexture made in the laboratory by a team of Australian-Japanese scientists kills up to 70% of bacteria and retains its effectiveness when transferred to plastic.

More than 30% of food produced for human consumption becomes waste, with entire shipments being rejected if bacterial growth is detected.

Research sets the stage for dramatically reducing waste, particularly in meat and dairy exports, as well as extending shelf life and improving the quality, safety and integrity of industrially packaged foods .

Emeritus Professor Elena Ivanova from RMIT University in Melbourne, Australia, said the research team had successfully applied a natural phenomenon to a synthetic material, plastic.

“Removing bacterial contamination is an important step in extending the shelf life of foods,” she said.

“We knew the wings of cicadas and dragonflies were very effective bacteria killers and could help inspire a solution, but replicating nature is always a challenge.

“We have now created a nanotexturizing that mimics the bacteria killing effect of insect wings and retains its antibacterial power when printed on plastic.

“This is a big step towards a natural, non-chemical and antibacterial packaging solution for the food and manufacturing industry.”

The research, published in Nanomaterials applied by ACSis a collaboration between RMIT, Tokyo Metropolitan University and the KAITEKI Institute of Mitsubishi Chemical.

In 2015, Australia exported $3.1 billion in food and agricultural exports to Japan, making it the 5th largest exporter of these products to the country.

How it works

Dragonfly and cicada wings are covered with a vast array of nanopillars – blunt spikes similar in size to bacterial cells.

When bacteria land on a wing, the nanopillar pattern separates the cells, rupturing their membranes and killing them.

“It’s like stretching a latex glove,” Ivanova said. “As it slowly stretches, the weakest point of the latex thins and eventually tears.”

Ivanova’s team developed their nanotexture by reproducing insect nanopillars and developing their own nanomodels.

To assess the antibacterial ability of the motif, bacterial cells were monitored in RMIT’s world-class microscopy and microanalytical facility.

The best antibacterial patterns were shared with the Japanese team, who developed a way to reproduce the patterns on plastic polymer.

Back in Australia, Ivanova’s team tested the plastic nanomodels and found the one that best replicated insect wings, but was also the easiest to fabricate and scale.

Ivanova said processing plastic was more difficult than other materials like silicon and metals, due to its flexibility.

“The nanotexturing created in this study holds up when used in rigid plastic. Our next challenge is to adapt it for use on softer plastics,” she said.

Since Ivanova and her colleagues discovered the bactericidal nature of insect wings a decade ago, they have worked to design the optimal nanomodel to harness the bacteria-killing powers of insects and use it on a range of materials.

Until recently, it was difficult to find a suitable technology to reproduce this nanotexturing on a scale suitable for manufacturing.

But now the technology exists to develop and apply antibacterial properties to packaging, among a range of other potential applications, such as personal protective equipment.

Their new research builds on a 2020 study of using insect-inspired nanomaterials to fight superbugs.

The team is keen to collaborate with potential partners in the next stage of research – scaling up the technology and determining the best ways to mass-produce the antibacterial packaging.

A pioneer of biomimetic antibacterial surfaces, Distinguished Professor Elena Ivanova leads the Mechano-Bactericidal Materials Research Group at RMIT’s Faculty of Science.

The research was supported by the Foundation for Australia-Japan Studies as part of the Rio Tinto Australia-Japan Collaboration Project.

Video: https://youtu.be/CyIrF5Jbrs8