By 
NEW DELHI: An Indian scientist’s team in the US has developed a new type of cotton face mask that can inactivate up to 99.9% of viruses, including Sars-Cov-2, within 30 minutes of daylight exposure. This means the wearer of the new mask can simply take a stroll in the sun to disinfect it. The innovation can curb transmission that occurs when viruses and bacteria that stick to the mask are transferred elsewhere if the person wearing it removes or touches it.
“The new fabric we developed for the mask can also be used to make protective suits,” Professor Nitin Nitin at the biological and agricultural engineering department in the University of California, Davis, told TOI. The 45-year-old, who hails from Amritsar, said the concept is feasible for large scale manufacturing since it builds on existing capabilities in both textile and materials industries.
Professor Gang Sun, who was part of the team, said they are now approaching industry partners to develop the new cotton fabric into different products.
Elaborating on the development, which was reported in the ACS Applied Materials & Interfaces journal this week, Sun said the team wanted to develop a fabric that would release reactive oxygen species (ROS) — oxygen-containing radicals which when exposed to light can remove microbes attached to the fabric’s surface.
At the same time, the fabric had to be washable, reusable and safe for the skin. For that, they needed the right photosensitizer — a compound that releases ROS upon exposure to light. “We had been working on using photosensitizers as biocidal agents on surfaces of materials,” said Sun. Biocidal agents destroy, render harmless or prevent the action of any harmful organism by chemical or biological means.
It took several months to explore potential chemicals that could provide the desired photo-induced biocidal functions on fibres, but the team finally narrowed down on Rose Bengal — a stain often used in diagnosing certain medical issues.
In tests, the team found that the fabric dyed with Rose Bengal inactivated 99.9% of T7 bacteriophage, a virus thought to be more resistant to ROS than some coronaviruses, within 30 minutes. Sun said the fabric would use the same mechanism against Sars-Cov-2, inactivating the virus by oxidising its genetic material and peptides.
The new mask was also able to kill 99.9% of bacteria and could be hand washed at least 10 times without losing its effectiveness.
Apart from the fabric’s obvious use in masks and protective suits, Nitin said its antibacterial and antiviral activity could be extended to any contact surfaces coated with fibres. “Even Rose Bengal dye when added to plastic surfaces could potentially have a protective effect,” he said.
