The advanced face mask kills bacteria and viruses with sun exposure

While face masks made from various cloth materials have been shown to filter nano-scale aerosol particles such as those released from a cough or sneeze, live bacteria and viruses on the face of the mask still present a risk of contagion for the wearer.

Now a team has developed a new cotton fabric that releases reactive oxygen species (ROS) when exposed to daylight, killing microbes attached to fabric surfaces while being washable, reusable and safe for the wearer.

It allows you to disinfect the face mask by leaving it outdoors in the sun or spending a longer period of time under office or building lights without other special decontamination measures.

Researchers made their antimicrobial tissues by attaching positively charged chains of 2-diethylaminoethyl chloride (DEAE-Cl) to ordinary cotton.

Then, they dyed the modified cotton in a solution of a negatively charged photosensitizer (a compound that releases ROS upon exposure to light), which attached itself to DEAE chains via strong electrostatic interactions.

The team found that a fabric made with a dye called Rose Bengal as a photosensitizer killed 99.9999% of the bacteria added to the fabric within 60 minutes of daylight exposure and inactivated 99.9999% of the T7 bacteriophage. a virus deemed more resistant to ROS than some coronaviruses – within 30 minutes.

Further tests showed that the material could be hand washed at least 10 times and constantly exposed to daylight for at least 7 days without losing its antimicrobial activity. The fabric shows the promise of making reusable, antibacterial / antiviral fabric face masks and protective suits, the researchers say.

The research was published in the American Chemical Society Applied materials and interfaces.

Since the onset of the Covid-19 pandemic, research to improve the effectiveness of face masks has increased dramatically. A battery-powered mask with built-in fans was built by LG, a team from MIT developed a mask with an integrated heated copper mesh, and another team designed a reusable silicone rubber mask with replaceable N95 filters.