With the current COVID19 pandemic situation wearing face mask in public is necessary and a must to protect one self and people around. When the user sneezes, cough or talks the face mask traps the droplets released by the wearer. Face mask is essential in public especially in places where social distancing is not possible. Experts and public health groups have repeatedly stressed the importance of wearing a mask for everyone whether they have any symptoms of the disease or not. Since certain individuals who do not realise that they have been affected may unknowingly spread the disease via aerosols while talking, sneezing or coughing.
Nanoscale aerosol particles released by coughing or sneezing are mostly filtered by the cloth material used to make facemasks which plays an important role in reducing the spread of contagious diseases like COVID-19. However the live pathogens like viruses and bacteria which are present in the aerosols trapped in the mask are still contagious. Wearers may unconsciously touch the mask or remove it and place it in a public space. When the wearer removes or touches the facemask the live pathogens trapped in the facemask could easily be transferred elsewhere which would anyway transmit the disease. Thus the purpose of wearing facemasks is lost. To address this problem researchers have developed a novel, reusable, durable cotton facemask which can kill 99.9999% bacteria and viruses within 60 minutes of exposure to sunlight. They used a unique fabrication process to develop the daylight induced antibacterial/antiviral property of the ingenious face mask which is washable reusable and safe to wear. Their groundbreaking work has been published in ACS Applied Materials & Interfaces.
This novel facemask, developed by Peixin Tang, Gang Sun, Nitin Nitin and team, can easily be disinfected by the wearer by spending an hour under the sun. Furthermore it can also be disinfected by artificial sources of light (building light) being far less intense than sunlight requires a longer period of time to disinfect the cloth mask. The antibacterial and antiviral property is due to the photo-induced fabric used to make the novel mask. The photo-induced fabric has been tested to have excellent washability and photostability which makes the fabric durable.
Upon exposure to light Reactive Oxygen Species (ROS) are produced by the photo-induced fabric used in the cotton facemask which kills the pathogenic microbes trapped in the mask. Thus ROS produced by the novel mask can be attributed to its antibacterial and antiviral property. Reactive Oxygen Species (ROS) are basically unstable chemical species which contain oxygen. ROS are highly reactive and are capable of causing damage to macromolecules such as lipids proteins and nucleic acids which makes it toxic for cells. Therefore microbes like bacteria and viruses are killed by ROS.
The team developed the antibacterial and antiviral novel fabric based on strong electrostatic interaction between cationic cotton fibers and anionic photosensitizers. To develop the novel fabric first the team attached positively charged chains of 2-diethylaminoethyl chloride (DEAE-Cl) to ordinary cotton fiber surface in order to form the cationic cotton. After which they dyed the cationic cotton in a solution containing anionic photosensitizes (a compound that can release Reactive Oxygen Species upon exposure to light) like rose Bengal and sodium 2-anthraquinonse sulphate. With the help of strong electrostatic interactions the negatively charged photosensitizer attached to the positively charged chains of 2-diethylaminoethyl chloride (DEAE-Cl). Thus the team developed an antimicrobial photo-induced fabric which upon exposure to light is capable of producing antibacterial/antiviral ROS which will kill the pathogen attached to the fabric.
As claimed by the research team within 60 min of exposure to daylight the fabric was able to kill 99.9999% bacteria and 99.9999% of T7 bacteriophage attached to it (T7 bacteriophage: a type of virus which according to scientists are presumed to be more resistant to ROS than coronaviruses). The team showed the anti microbial property of the ingenious fabric:
- By measuring the levels of ROS produced by the fabric
- Testing its antibacterial activity against bacteria like E.coli and L.innocua
- Testing its antiviral property against viruses like T7 bacteriophage
As claimed by the team the fabric showed significant bioprotective properties making it suitable to combat not only COVID19 but also other contagious diseases which get transmitted via aerosols.
The research team even tested the modified cotton fabric’s washability, photostabilty and durability. The team demonstrated that the novel fabric did not lose its antimicrobial property even after constant exposure to sunlight for a period of 7 days and 10 times of hand washing.
As claimed by the researchers the novel fabric has the potential to become the ideal material for making washable, reusable, antibacterial and antiviral face masks and protective suits which can be easily sterilized by the wearer by simply exposing the material to daylight. This bioprotective material will play a far more significant role in controlling contagious diseases with respect to existing masks and protective suits made of ordinary material. Reusable and sustainable PPE made using the photo-induced antibacterial and antiviral fabric developed by the team would provide improved biological protection compared to traditional PPEs.
Face masks are a necessity in the current situation for controlling the pandemic. However droplets laden with pathogenic microbes like bacteria and viruses trapped within the face masks makes it contaminated. Once the contaminated masks are touched by the wearer or are removed and placed in public spaces the pathogenic microbes can easily be transmitted to fingers or other places. This defeats the very purpose of wearing masks which is to prevent the transmission of contagious diseases like COVID19. With this novel facemask which can be sanitized by the user themselves, without any extra effort, by simply taking a walk under the sun will ensure the protection of the user and people around. If one wants to avoid the sun the ingenious mask can also be sanitized with artificial light sources just that a little longer time will be required. For sanitization of the PPEs and face masks made with the photo-induced fabric one will not require any disinfecting agent like sanitizers or detergents but simply a source of light which is widely and easily available.
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
Available from: https://pubs.acs.org/doi/10.1021/acsami.0c15540