“We often look to mother nature for interesting things. When scientists take a look at these things, it often involves the nanoworld,” said Kevin Walsh, associate dean of research and facilities, professor of electrical engineering at UofL’s and founding director of UofL’s Micro/Nano Technology Center (MNTC).

Cicada wings’ antibacterial properties in particular interested University of Louisville engineers. Along with UofL biologists, the team analyzed the nanostructure of the insects’ wings and developed a nanofabrication technique to replicate it for potential use in spaces where bacteria are undesirable, such as food service, health care facilities and medical devices.

The team, led by Chuang Qu, Walsh and Mark Running, has developed a process to synthesize a surface material that mimics the wings’ structure and has the same antibacterial and water repellant properties as the wings that inspired it. The development and testing of the innovative manufacturing process was made possible through the use of , which include a scanning electron microscope (SEM) and nanomaterial production capabilities.

With the help of an SEM, scientists can see that cicada wings’ surface consists of tiny, bowling-pin-shaped structures with a diameter of around 100 nanometers – about one-thousandth of the diameter of a human hair. The wings owe their antibacterial properties to the spike-shaped tops which act like daggers, piercing the cellular membranes of bacteria that have the misfortune of landing on them, ultimately killing the bacteria.

To replicate the cicada wings’ nanopillar cone structure, Qu, a senior research engineer at Speed School specializing in advanced nanofabrication, developed a two-step process of self-assembly and glancing-angle deposition (GLAD).

“All the structures we discovered under the microscope are challenging to recreate because they are so small and three-dimensional,” Qu said. “Using a two-step self-assembly plus glancing angle deposition, we were able to recreate the structure and confirm that, like their cicada wing template, they have these antimicrobial properties.”

The manufacturing method consists of two processes. First, bases of the nanopillars are created using self-assembly, in which the material spontaneously falls into place. To create the tips of the bowling pin shapes, the researchers used GLAD, a technique in which physical vapor is deposited onto the base structure at an oblique angle. This procedure reduces the number of steps required to manufacture complex nanostructure materials that is cheaper and more scalable than other methods.

To verify the antibacterial effect of the nanostructure they had developed, the team tested it using E. Coli, common bacteria that have a fairly tough cell wall. Examining the effects of the manufactured surface on bacteria using the SEM at MNTC, the researchers found that the new material functioned in the same way as the cicada wings – destroying the bacteria with its dagger-like spikes.

Since the cicada wings and the replica material rely on physical nanostructures to kill the bacteria and can be made of virtually any material, the surfaces avoid possible negative effects of chemical antimicrobials in biomedical applications.

“We didn’t know it was going to be physical and that we would be able to detect it, so I was really happy that we were able to determine that,” said Mark Running, a UofL biology professor and coauthor of the .

While further work is needed to fully adapt the material to commercial use, it has potential for applications such as on doorknobs or other surfaces that need to be kept clean and germ free, food preparation surfaces and implantable medical devices that are prone to bacterial infection. The team has filed a provisional patent on a process called “inverted GLAD” to create materials such as the cicada wing replication and is seeking to hire students to assist with additional research.

“The challenges are how to scale the production up to larger areas and how to apply them to curved surfaces,” Walsh said. “Right now, we can just use it on flat surfaces.”

UofL’s MNTC facilities are available for use by researchers within and outside of UofL, as well as businesses conducting product research and development. It is one of 16 facilities at universities nationwide funded by the National Science Foundation to support research and industry. MNTC is one of eight advanced manufacturing facilities in the , a consortium of resources at UofL and the University of Kentucky.

Researchers at the University of Louisville  are working at the forefront in combating these pathogens. The CPM has been testing the effectiveness of new drugs against P. aeruginosa under a contract with the National Institutes of Health since 2013, and a new contract from the U.S. Food and Drug Administration will expand the center’s work in testing new drugs against this pathogen. Under the new two-year, $933,606 contract, CPM will develop a validated model for screening antimicrobial drugs against P. aeruginosa.

“This model likely will play an important role in drug development pipelines leading to identification of new antimicrobial drugs,” said Matthew Lawrenz, PhD, associate professor of microbiology and immunology who is leading the research. “Researchers at UofL and from around the world will use the model to screen new antimicrobials against multi-drug resistant bacteria prior to clinical trials.”

Forest Arnold, DO, hospital epidemiologist for UofL Hospital and associate professor in the Division of Infectious Diseases in the UofL School of Medicine, said multi-drug resistant bacteria and XDR bacteria, those with resistance to all existing antibiotics, are evolving faster than the drugs to kill them.

“The germs get smarter as we make new drugs. If we are going to stay on top of them, we need new antibiotics, especially new classes of antibiotics — those with a new mechanism of action that the germ hasn’t seen before,” Arnold said.

Infections with MDR bacteria are particularly threatening for patients with weakened immune systems, those who have had multiple rounds of treatment with antibiotics, and in patients using devices such as ventilators and blood catheters. Since these bacteria are now resistant to many of the antibiotic drugs used to treat them, they can lead to severe infections and death.

“If you have an infection with a bacterium we don’t have an antibiotic to treat, it could kill you,” Arnold said.

P. aeruginosa is common in the environment and in otherwise healthy people, it may cause relatively minor of the ear, skin or eye. However, in people with weakened immune systems or in hospital settings, P. aeruginosa can cause serious, life-threatening infections of the blood, lungs, digestive tract or tissue. Infected wounds will have a green pus or discharge and a fruity smell.

The validated animal model, to be developed by UofL researchers with collaborators at the University of Kentucky and the University of Wisconsin, will be used to test new compounds developed by drug companies and research labs around the world against P. aeruginosa. This model will allow testing against multiple strains of pseudomonas and will give more detailed information about the effectiveness of the drugs being tested.

“The previous methods we used for testing the drugs provided basic information about a compound’s effectiveness. This new model will allow us to test anything from older classes of antibiotics to brand new classes and will provide information on dosing and scheduling. In addition, we will be able to test different strategies, such as immunomodulation – targeting the host to better respond to the infection as opposed to directly killing the bacteria,” Lawrenz said.

The CPM’s new contract with the FDA will take advantage of the sophisticated resources at the , located on the UofL ShelbyHurst Campus, which provide the environment necessary for this work.

“This new contract from the Food and Drug Administration supports the development of a model for understanding how bacteria build resistance to current commercially available antibiotics, which in turn, will lead to the discovery of new drugs or methods to combat a variety of infectious diseases,” said Robert Keynton, PhD, interim executive vice president for research and innovation at UofL. “The UofL Center for Predictive Medicine and the Regional Biocontainment Laboratory represents a significant investment in infrastructure, faculty and staff by the university in the field of emerging infectious diseases, which is one of our research and training strategic priorities.”