During the COVID-19 pandemic, many people are accustomed to wearing cotton face masks in public. However, viruses and bacteria stick to them and are transferred to another location when the wearer removes the mask or touches it. Scientists have developed a special type of cotton face mask that kills up to 99.9999% of bacteria and viruses within 60 minutes of exposure to daylight.
Made from a variety of fabric materials, face masks filter nano-sized aerosol particles. These are the ones that stand out when you cough or sneeze. This helps reduce the spread of disease, including COVID-19.
But live bacteria and viruses on the surface of the mask can still be infectious. The scientists wanted to develop a new cotton fabric that would release reactive oxygen species (ROS) when exposed to daylight. In this way, it could kill microbes adhering to the surface of the tissue. It was important to scientists that masks were washable, reusable and safe for the wearer.
As a result, the scientists managed to realize their plans.
They created antimicrobial tissues by attaching positively charged chains of 2-diethylaminoethyl chloride to regular cotton. The researchers then dyed the modified cotton in a negatively charged photosensitizer solution. It is this compound that allows ROS to be released upon exposure to light.
Scientists conducted an experiment and found that their tissue killed 99.9999% of the bacteria added to the tissue. It took 60 minutes of exposure to daylight. Further testing showed that the material can be washed by hand at least 10 times and continuously exposed to daylight for at least 7 days without losing the antimicrobial properties of the fabric.