A new textile coating can not only repel liquids like blood and saliva but also prevent viruses from adhering to the surface, researchers say.

Masks, gowns, and other personal protective equipment (PPE) are essential for protecting healthcare workers. However, the textiles and materials used to make such items can absorb and carry viruses and bacteria, inadvertently spreading the disease the wearer sought to contain.

When the coronavirus spread among healthcare professionals and left PPE in short supply, finding a way to provide better protection while allowing for the safe reuse of these items became paramount.

“Recently there’s been focus on blood-repellent surfaces, and we were interested in achieving this with mechanical durability,” says Anthony Galante, a PhD student in industrial engineering at the University of Pittsburgh and lead author of the paper in in the journal ACS Applied Materials and Interfaces.

“We want to push the boundary on what is possible with these types of surfaces, and especially given the current pandemic, we knew it’d be important to test against viruses.”

Textile coating withstands serious scrubbing

The coating’s ability to withstand ultrasonic washing, scrubbing, and scraping makes it unique. With other similar coatings currently in use, washing or rubbing the surface of the textile reduces or eliminates its repellent abilities.

“The durability is very important because there are other surface treatments out there, but they’re limited to disposable textiles. You can only use a gown or mask once before disposing of it,” says Paul Leu, coauthor and associate professor of industrial engineering, who leads the LAMP Lab in the School of Engineering. “Given the PPE shortage, there is a need for coatings that can be applied to reusable medical textiles that can be properly washed and sanitized.”

To test the new coating, Galante ran it through tens of ultrasonic washes, applying thousands of rotations with a scrubbing pad (not unlike what you might use to scour pots and pans), and even scraping it with a sharp razor blade. After each test, the coating remained just as effective.

The researchers worked with the Charles T. Campbell Microbiology Laboratory’s Research Director Eric Romanowski and Director of Basic Research Robert Shanks, in the ophthalmology department to test the coating against a strain of adenovirus.

“As this fabric was already shown to repel blood, protein, and bacteria, the logical next step was to determine whether it repels viruses. We chose human adenovirus types 4 and 7, as these are causes of acute respiratory disease as well as conjunctivitis (pink eye),” Romanowski says.

“It was hoped that the fabric would repel these viruses similar to how it repels proteins, which these viruses essentially are: proteins with nucleic acid inside. As it turned out, the adenoviruses were repelled in a similar way as proteins.”

Hospital gowns and waiting room chairs

The coating may have broad applications in health care: everything from hospital gowns to waiting room chairs could benefit from the ability to repel viruses, particularly ones as easily spread as adenoviruses.

“Adenovirus can be inadvertently picked up in hospital waiting rooms and from contaminated surfaces in general. It is rapidly spread in schools and homes and has an enormous impact on quality of life—keeping kids out of school and parents out of work,” says Shanks. “This coating on waiting room furniture, for example, could be a major step towards reducing this problem.”

The researchers will next test the effectiveness against betacoronaviruses like the one that causes COVID-19.

“If the treated fabric would repel betacornonaviruses, and in particular SARS-CoV-2, this could have a huge impact for health care workers and even the general public if PPE, scrubs, or even clothing could be made from protein, blood-, bacteria-, and virus-repelling fabrics,” says Romanowski.

At the moment, researchers apply the coating using drop casting, a method that saturates the material with a solution from a syringe and applies a heat treatment to increase stability.

But the researchers believe the process can use a spraying or dipping method to accommodate larger pieces of material, like gowns, and can eventually scale up for production.

Source: University of Pittsburgh

Related

Lasers could turn regular metal surfaces into bacteria killers

Special UV lights could kill coronavirus on surfaces

Coating could mean the end of foggy glasses

A new coating prevents fogging on transparent surfaces, researchers report.

Going into a warm humid environment from the cold can cause eyeglasses or camera lenses to fog up, but the new coating uses sunlight to clear things up.

Since the only energy source required is the sun, the coating works especially well for wearable items such as glasses and goggles. Researchers made the transparent durable coating, which is just a few nanometers thick, of gold nanoparticles embedded in non-conductive titanium oxide.

“Our coating absorbs the infrared component of sunlight along with a small part of the visible sunlight and converts the light into heat,” says lead author Christopher Walker, a doctoral student working with Dimos Poulikakos, a professor at ETH Zurich. The process heats the surface up about 3 to 4 degrees Celsius—the difference in temperature that prevents fogging.

Heat also solves the problem of fogging on car windows. Warm air from the in-vehicle heating system heats the front windshield, while the rear window uses a grid of electrical heating elements. Unlike these methods, the researchers’ new coating works passively.

“Normally, it’s dark surfaces that absorb light and convert it into heat,” says Efstratios Mitridis, another doctoral student in Poulikakos’s group. “But we’ve created a transparent surface that has the same effect.”

Condensation occurs on a surface whenever there is a sudden drop in temperature or increase in humidity, forming tiny droplets of water that disperse incident light in different directions in much the same way as atmospheric fog.

As an alternative to using heat to prevent fogging, hydrophilic agents can coat susceptible surfaces. Because they attract water, these agents ensure that the condensation forms an even thin film of liquid over the surface rather than separate droplets. Anti-fog sprays for glasses usually work on this principle.

Now, tests have shown that when exposed to sunlight, fogged surfaces coated with gold nanoparticles and titanium oxide clear four times faster than surfaces treated with a normal anti-fog agent.

“Spray treatments often lose their effect after a while because the anti-fog film dries up or becomes unevenly distributed,” Walker says. “A durable coating like ours lasts much longer than a spray treatment, which you have to apply virtually on a daily basis.”

The scientists say they plan to bring the new method to market, in collaboration with an industry partner.

“We’re looking to refine our already robust coating to ensure it lasts for years, and we want to take the technology from lab scale to industry scale,” Walker says.

Source: ETH Zurich

Related

Why beers warm up faster in humid weather

To generate more solar power, put this material on glass

Spray coating could pave way for cheaper solar cells