Researchers from the University of California, Davis in the United States have designed a new cloth-based face mask that can destroy up to 99.99 per cent of bacteria, viruses, and other pathogens within an hour of daylight exposure.

The researchers noted that this cotton cloth mask can be washed 10 times and can be continuously exposed to sunlight for at least a week. This will not deteriorate its antimicrobial activity.

The study was published in the journal ACS Applied Materials and Interfaces.

Methodology

The researchers aimed to design a new cotton fabric that 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 user.

The researchers made their antimicrobial fabrics by attaching positively charged chains of 2-diethyl aminoethyl chloride (DEAE-Cl) to ordinary cotton.

They dyed the modified cotton in a solution of a negatively charged photosensitizer — a compound that releases ROS upon exposure to light — which attached to the DEAE chains by strong electrostatic interactions.

The researchers noted that people can disinfect their cloth mask during their lunch hour outside in the sun, or by spending a longer period of time under office or building lights, which are much less intense than sunlight.

Results

The team noticed that the photo-sensitizer killed 99.9999 per cent of bacteria added to the fabric within an hour of daylight exposure and inactivated 99.9999 per cent of T7 bacteriophage —a virus thought to be more resistant to ROS than some coronaviruses — within half an hour.

The fabric shows promise for making reusable, antibacterial, or antiviral cloth face masks and protective suits, the researchers said.

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