Cloth face masks that can be disinfected by the sun

Date:
November 11, 2020
Source:
American Chemical Society
Summary:
Researchers have developed a special type of cotton face mask
that kills up to 99.9999 percent of bacteria and viruses within
60 minutes of daylight exposure.



FULL STORY ========================================================================== During the COVID-19 pandemic, many people have become accustomed to
wearing cotton face masks in public places. However, viruses and bacteria
that stick to the mask could be transferred elsewhere when the wearer
removes or touches it.

Now, researchers 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 -- such as those released by a cough or sneeze -- potentially
helping to reduce the spread of diseases, including COVID-19. But
live bacteria and viruses on the surface of the mask could still be
contagious. Peixin Tang, Gang Sun, Nitin Nitin and colleagues wanted to
develop 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 wearer. Then, a
person could 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.

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 photosensitizer (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 99.9999% of bacteria added
to the fabric within 60 minutes of daylight exposure and inactivated
99.9999% 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 handwashed 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.


========================================================================== Story Source: Materials provided by American_Chemical_Society. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Peixin Tang, Zheng Zhang, Ahmed Y El-Moghazy, Nicharee Wisuthiphaet,
Nitin Nitin, Gang Sun. Daylight-Induced Antibacterial and
Antiviral Cotton Cloth for Offensive Personal Protection. ACS
Applied Materials & Interfaces, 2020; 12 (44): 49442 DOI:
10.1021/acsami.0c15540 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/11/201111144407.htm

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