Sharks are oft-misunderstood creatures that usually provoke a feeling of fear in people. However, researchers are using the creatures—their skin in particular—for inspiration to develop a new type of coating that can be used to fight bacteria.
Powerful bacteria infections that are resistant to antibiotics—often called “super bugs”—are becoming a plague in hospitals. The US Centers for Disease Control and Prevention (CDC) estimates that these bugs—infecting hospital patients who are already immune compromised—cause 2 million infections and 23,000 deaths in the United States every year.
Hospitals and other patient facilities are seeking stronger anti-bacterial agents and coatings to help prevent surfaces from being sources of these bugs. For example, researchers at the University of Massachusetts Amherst (UMass) have developed a material that can be used as a coating for “producing durable multifunctional surfaces that decrease microbial attachment and inactivate attached microorganisms,” researchers wrote in an abstract for a paper published in ACS Materials and Applied Interfaces.
Researchers at the University of Massachusetts Amherst have developed a new anti-bacterial coating by using inspiration and material from shark skin. (Image source: Shutterstock.com)
The researchers observed how shark skin “has unique characteristics that prevents fouling of barnacles, algae, and other types of bio-foulants on skin,” Feyza Dundar Arisoy, a graduate research assistant in the Department of Polymer Science and Engineering at UMass, explained to Design News.
“When shark-skin features are reduced down to bacteria size, the same pattern prevents bacteria fouling on the surface,” she told us. “However, the limitation intrinsic to all microtopographic patterned surfaces—that bacteria will accumulate on the surface in a sufficient amount of time—makes this method insufficient alone.”
Printing Shark Skin
To solve that limitation, the team used solvent-assisted, soft nanoimprint lithography on a polyethylene terephthalate (PET) substrate to fabricate the coating. They combined antifouling shark-skin patterns with antibacterial titanium dioxide and nanoparticles from which shark-skin microstructures were imprinted as their materials, Arisoy said.
“We designed polymer and ceramic composite materials with photocatalytic titanium dioxide nanoparticles and imprinted them in shark-skin patterns,” she explained. “Titanium dioxide nanoparticles kill a variety of microorganisms without bleaching out.”
The coating can be used on high-touch surfaces in hospitals, such as bed rails and door knobs, to help prevent the spread of infections, Arisoy said. Moreover, the printed materials can be tuned for different applications and environments—from soft polymers to extremely hard and wear-resistant ceramics.
In tests, the materials developed by the team reduced the attachment of E. coli by 70 percent compared to smooth films used for the same purpose, Arisoy said. In even more optimal results, shark skin surfaces with titanium dioxide nanoparticles exposed to ultra-violet light for one hour killed more than 95 percent of E. coli and 80 percent of Staphylococcus aureus—two common bacterial infections found in hospitals, she said.
“To the best of our knowledge, this work represents the first reported use of antibacterial nanoparticles in shark-skin patterns,” Arisoy said. “The combination of passive and active strategies on a single surface is the most promising material design strategy to control bacterial fouling.”
The team currently is continuing its work to develop a roll-to-roll manufacturing process for photocatalytic shark-skin surfaces for widespread use in practical applications, she added.
Elizabeth Montalbano is a freelance writer who has written about technology and culture for 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco, and New York City. In her free time, she enjoys surfing, traveling, music, yoga, and cooking. She currently resides in a village on the southwest coast of Portugal.
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