The antiviral layer attacks the respiratory droplets and reduces the infectivity of mask wearers-ScienceDaily

With this in mind, researchers have developed a new concept for masks aimed at reducing infections in the wearer. The central idea, supported by the National Science Foundation through the RAPID grant, is to change the mask fabric with an antiviral chemical that can disinfect exhaled respiratory droplets.

By simulating inhalation, exhalation, coughing, and sneezing in the lab, researchers found that the non-woven fabrics used in most masks worked well to demonstrate the concept. For example, a lint-free wipe with a fiber density of only 19% disinfected up to 82% of the escaped respiratory droplets by volume. Such fabrics did not make breathing more difficult and the chemicals on the mask did not exfoliate during the simulated inhalation experiment.

The study will be published in the journal on October 29th Matter..

The importance of protecting others

“Masks are probably the most important component of personal protective equipment (PPE) needed to fight a pandemic,” said Jiaxing Huang of Northwestern University, who led the study. “I quickly realized that masks not only protect the wearer, but more importantly, they protect others from exposure to the droplets (and bacteria) they emit.

“Some people don’t think they need personal protection, so wearing a mask seems pretty confusing,” Huang added. “Maybe you should call it Public Health Equipment (PHE) instead of PPE.”

Huang is a professor of materials science and engineering at Northwestern University’s McCormick Engineering School. Graduate students Haiyue Huang and postdoctoral fellow Hun Park are both members of Huang’s lab and co-lead authors of this paper.

“If you have an infectious respiratory disease, controlling the source of the virus is the most effective way to prevent the spread of the virus,” said Haiyue Huang, 2020 Ryan Fellowship Winner. .. “After they leave the source, the respiratory droplets become more diffuse and more difficult to control.”

Goals and results

The mask can block or reroute the exhaled respiratory droplets, but many droplets (and the viruses embedded in them) still escape. From there, droplets containing the virus can infect others directly or land on the surface and indirectly infect others. Huang’s team sought to chemically alter the escape droplets to inactivate the virus more quickly.

To achieve this, Huang can (1) not make breathing difficult, (2) load molecular antiviral agents such as acids and metal ions that are easily soluble in escaped droplets, and (3) mask fabrics. I tried to design. ) Do not contain volatile chemicals or easily removable materials that the wearer may inhale.

After conducting multiple experiments, Huang and his team selected two well-known antiviral chemicals, phosphoric acid and copper salt. Neither of these non-volatile chemicals was attractive because they could not be vaporized and inhaled. And both create a local chemical environment that is detrimental to the virus.

“The structure of the virus is actually very delicate and’fragile’,” says Huang. “If any part of the virus malfunctions, it loses its ability to infect.”

Huang’s team has grown a layer of conductive polymer polyaniline on the surface of the mask fabric fibers. This material adheres strongly to the fibers and acts as a reservoir for phosphates and copper salts. Researchers have found that even loose fabrics with a fiber filling density of about 11%, such as medical gauze, change 28% of the exhaled respiratory droplets by volume. For tighter fabrics, such as lint-free wipes (the type of fabric normally used for cleaning in the lab), 82% of the respiratory droplets have changed.

Huang, the current study has developed its own version of this chemical modulation strategy in other researchers, especially in other parts of the world, and provides a scientific basis for further testing virus samples or even patients. I want to do it.

“Our research has become open knowledge. We hope that more people will participate in this effort to develop tools to enhance our public health response,” Huang said. Mr. says. “The work is done almost entirely in the lab during the campus shutdown. It can contribute to energy and talent for researchers in the non-biological aspects of science and engineering, as well as researchers with many resources and connections. I would like to show. “

This work was primarily supported by the National Science Foundation (RAPID DMR-2026944).