Masks and gowns are crucial to protect health workers from the spread of viruses, but they only do so much. Germs can still latch onto the material that protective equipment is made of, and diseases can spread when people touch those off those masks or touch their gowns. What if, like water sliding off a raincoat, viruses could be repelled by the textiles used for PPE, clothing, and even the seats in a hospital waiting room?
University of Pittsburgh researchers have created a washable textile coating that repels liquids, such as blood and saliva, and also prevents viruses from adhering to its surface. Their work, which was recently published in the journal ACS Applied Materials and Interfaces, began before the COVID-19 pandemic, but the researchers see it being especially relevant now.
Not only could this coating potentially improve how protective PPE is, says Paul Leu, coauthor of the research, associate professor of industrial engineering at Pitt, and head of the school’s Laboratory for Advanced Materials—it could also help address critical PPE shortages, such as what hospitals across the world are currently facing. “One of the main reasons [for shortages] is because a lot of medical textiles are disposable. They’re single use—you use it once, then throw it away,” he says. “Because our treatment is wash-stable, it could potentially be incorporated into reusable medical textiles.”
The liquid- and virus-repellent coating is made with polytetrafluoroethylene (PTFE, the same polymer that makes Teflon nonstick) and polypropylene microfibers. In their research so far, the Pitt team applied this coating to textiles through drop casting, a method to coat materials by dropping the solution from a syringe. Anthony Galante, a PhD student in industrial engineering at Pitt and lead author of the paper, says they believe it could be sprayed on or applied via dipping for larger-scale fabrication.
Protective coatings, including for medical textiles, aren’t new, but Leu and Galante say that they’re often not very durable. “If you simply scratch it with your fingernail or a tissue, you already start to lose some of that functionality. There are other protective barrier coatings, but usually you have to dispose of the textile after you’ve used it once,” Leu says. “The novelty that we see [in ours] is in the wash stability and mechanical durability.”
In their testing, they ran the fabric through ultrasonic washes, which essentially scour the fabric with an abrasive sponge. The coated textile can withstand more than 100,000 cycles of such scrubbing. “We have videos in our work where we’re slicing it and also scratching it with a fresh razor blade, and it still demonstrates the liquid repellency after this,” Galante says. “After the slicing, the fabric is basically destroyed, it has holes in it, but the area where the fabric exists still is repellant.”
Though there are many coatings meant to repel liquid droplets, many haven’t been explicitly tested against viruses. Pitt researchers tested theirs with adenovirus types 4 and 7 which, like SARS-Cov-2, the virus that causes COVID-19, cause respiratory lung infections. Those viruses also spread in a similar way, Galante says.
The team plans to further test this coating against coronaviruses, specifically SARS-CoV-2, and also look into scaling its application up to cover larger surface areas. Once that work is done, the team will have to collaborate with manufacturing providers to turn this coating into products, whether medical or otherwise. “I think potentially this is something you could also apply to everyday clothing outside of a healthcare setting,” Leu says. “Maybe a pillow, maybe a blanket.” The cost issue of adding on such a coating will have to be figured out as well, but in a world where more pandemics are expected, virus-repellent fabric may be worth the price.