New face masks can be disinfected by the sun

New face mask disinfected by the sun

Researchers are reporting in ACS Applied Materials & Interfaces have developed a special type of cotton face mask that kills up to 99.9999% of bacteria and viruses within 60 minutes of daylight exposure.

Face masks made of various cloth materials can filter nanoscale aerosol particles, released by a cough or sneeze potentially limiting the spread of COVID-19. This means that a normal cotton face mask could still be contagious and so developers strived to innovate with a new protective face mask.

The newly developed mask would release reactive oxygen species (ROS) when exposed to daylight, killing microbes attached to the fabric’s surfaces while being washable, reusable and safe for the wearer. Then, a person could disinfect their cloth mask for an hour outside in the sun, or by spending a longer under normal lighting, which is much less intense than sunlight.

The researchers made their antimicrobial fabrics 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 photosensitiser (a compound that releases ROS upon exposure to light), which attached to the DEAE chains by strong electrostatic interactions. The team found that a fabric made with a dye called rose Bengal as the photosensitizer killed 99.99% of bacteria added to the fabric within 60 minutes of daylight exposure and inactivated 99.99% of T7 bacteriophage, a virus thought to be more resistant to ROS than some coronaviruses within 30 minutes.

Further testing 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 promise for making reusable, antibacterial/antiviral cloth face masks and protective suits, the researchers say.

The authors acknowledge funding from the COVID-19 Research Accelerator Funding Track Program at the University of California, Davis and the California Department of Pesticide Regulation.

Source: ACS Publication

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