New materials and coatings could make fabric inactivate or repel viral particles
Wearing masks and other personal protective equipment (PPE) can slow the spread of COVID-19. The U.S. Centers for Disease Control and Prevention recommends everyone wear some kind of face covering in public places, especially where social distancing is difficult to maintain. And health workers are donning additional coverings, such as gowns. Yet all such protective gear shares one significant problem: people still risk becoming infected with the novel coronavirus if they accidentally touch areas of the fabric that are contaminated with viral particles. So researchers are working to develop cloth that could inactivate or repel coronaviruses—ideally including the one that causes COVID-19—and other pathogens.
People can transfer infectious particles to their hands if they touch the front of a mask during use or when they remove gowns or other PPE, according to Chandan Sen, director of the Indiana Center for Regenerative Medicine and Engineering at Indiana University. He and his colleagues have been developing a way to render those particles and other infectious agents harmless. The team researches “electroceutical” materials that wirelessly “generate electric fields across the surface of the fabric,” Sen says. Those fields can disrupt the behavior of bacteria or viruses on the cloth.
“The beauty of this [technology] is the inherently simple design,” he says. The polyester material is printed with alternating spots of silver and zinc resembling polka dots. They are one to two millimeters wide and spaced one millimeter apart. When the electroceutical material is dry, it functions as an ordinary fabric. But if it gets dampened—say, with saliva, vapor from a coughed up droplet or other bodily fluids—ions in the liquid trigger an electrochemical reaction. The silver and zinc then generate a weak electric field that zaps pathogens on the surface.
The researchers co-developed the material with the biotechnology company Vomaris Innovations in 2012. Last year they showed that the technology could be used to treat bacterial biofilms in wounds. A clinical trial is underway to further evaluate the fabric’s effectiveness as a Food and Drug Administration–cleared dressing for wound care, Sen says.
In response to the COVID-19 pandemic, Sen’s team tested its existing material on a different coronavirus strain that causes a respiratory illness in pigs and on an unrelated type of pathogen called a lentivirus. “We wanted to know how broadly this principle could be applicable,” he says. In a study posted on the preprint server ChemRxiv in May, Sen’s team reported that its electroceutical fabric destabilized both viruses, leaving them unable to infect cells. The researchers plan to submit the results to a peer-reviewed journal as well.
To study the fabric’s action, they placed a liquid solution containing viral particles onto the electroceutical fabric and a polyester control fabric without the metal dots. After the droplets were fully absorbed, and the samples had rested for one to five minutes, the researchers recovered viral particles from both fabrics and tested whether they could still infect the types of cells they typically target.
“The data presented here show that, of the total virus that was recovered, a significant percentage was inactivated,” says Jeff Karp, a professor of medicine at Brigham and Women’s Hospital in Boston and co-leader of an N95 respirator working group at the Massachusetts General Brigham Center for COVID Innovation. Karp, who was not involved with the study, adds that the researchers did not test all of the virus that they had placed on the cloth. “In fact, the majority of virus was not recovered from the textiles examined in this study,” he says. Sen responds that his team focused on sampling only enough viral particles to show that the fabric had rendered them unable to infect cells. The researchers recovered roughly 44 percent of the particles from the electroceutical fabric samples that had rested for one minute. And they retrieved 24 percent of them from the samples that had rested for five minutes.
The material’s virus-fighting abilities have not been tested specifically on SARS-CoV-2, the coronavirus that causes COVID-19. The researchers’ findings with the two viruses they studied, however, gave them “hope that this could apply more widely,” Sen says. He adds that large-scale manufacturing of the electroceutical fabric is already possible and that the costs of producing it are relatively low. The metal dots could be printed directly onto the front surfaces of masks, he suggests. Or an electroceutical fabric could be inserted between the front of a mask and the wearer’s face.
If a virus-stopping PPE material were widely available, it could limit the novel coronavirus’s ability to spread. “There is a huge unmet need to better understand modes of viral transfer that lead to virus transmission,” Karp says. “As we develop a better understanding of this, there is a huge immediate need to develop and quickly apply solutions that can reduce transmission.”
Metal dots are not the only potential approach. Paul Leu, director of an advanced materials laboratory at the University of Pittsburgh, and his colleagues are developing a textile coating that repels bodily fluids, proteins and bacteria. It also repels one strain of adenovirus that causes respiratory illness and another that causes conjunctivitis, as reported in ACS Applied Materials & Interfaces in April. Leu’s team has also not tested the material with the novel coronavirus itself, however. “The main thing with testing [the coating on] SARS-CoV-2 is the biosafety level you need to test it, because it’s very hazardous,” he says. Still, his team plans to see how well textiles with this coating repel a different coronavirus.
Leu says the coating, which remains repellent even after ultrasonic washing and scraping with a razor blade, could make PPE safer for wearers to take off. It could also be used on hospital bed linens, drapes and waiting room chairs, the researchers note in the study. But Leu points out that the coating is intended for use with medical textiles that are already considered reusable. His team has not tested it on single-use masks or N95s, but he thinks it could potentially damage them. Still, he says, the coating could work well for cloth masks such as those now being worn by many among the general public.
By developing materials that kill or repel viruses, researchers hope to make masks and other protective gear safer to remove and more effective against all viruses. “If the common person were to have PPE that wouldn’t spread infection,” Sen says, “I think that’s a big, big deal.”