Researchers from the Indian Institute of Technology Mandi have developed a virus-filtering, self-cleaning and antibacterial material that can be used to make face masks and other PPE equipment. The research team led by Dr Amit Jaiswal, Assistant Professor, School of Basic Sciences, IIT Mandi, and consisting of research scholars, Praveen Kumar, Shounak Roy and Ankita Sarkar has used such materials that are a hundred thousand times smaller than the width of the human hair to confer antimicrobial properties to polycotton fabric.
Results of this work have recently been published in the prestigious journal of the American Chemical Society – Applied Materials & Interfaces. Facemasks have (or must) become a default piece of apparel to be worn in public in these pandemic times. They are largely designed to act as a physical barrier between the wearer and the external environment, but in reality, must also act as anti-microbial agents to inhibit or kill pathogens. This is especially important in the case of reusable masks, which are a necessary alternative to single use masks that add to littering and pollution issues, and secondary infections. “Keeping the urgency of the pandemic situation and cost-effectiveness in mind, we have developed a strategy to repurpose existing PPEs, especially face masks, by providing an antimicrobial coating to these protective clothing/textiles,” said Dr Jaiswal.
The team has incorporated nanometre-sized sheets of molybdenum sulphide, MoS2, the sharp edges, and corners of which act as tiny knives that pierce bacterial and viral membranes, thus killing them. “The ‘nanoknife’-modified fabrics demonstrated excellent antibacterial activity even after 60 cycles of washing,” said the lead researcher, which makes this an excellent way to reuse masks and reduce biological waste generation.
Dr Jaiswal reminds us that improperly disposed off PPEs are a serious secondary source of transmission, and having reusable antimicrobial masks can help circumvent this risk. The reusability of the fabric will also enable it to be integrated with homemade masks.
In addition to puncturing the microbial membranes, the nanosheets of molybdenum sulfide enable disinfection when exposed to light. Molybdenum sulphide exhibits photothermal properties, i.e., it absorbs solar light and converts it into heat, which kills the microbes. “Within 5 min of solar irradiation, all the MoS2-modified fabrics showed 100% killing of both E. coli and S. aureus,” wrote the authors in their recently published paper. Thus, merely hanging out the masks in bright sunlight can clean the mask and make it ready to wear again.
The researchers have developed prototypes of a 4-layered face mask using the MoS2 modified fabric. They report that these masks, in addition to killing microbes and being light-cleanable, can also filter more than 96 per cent of particles that are in the size range of the COVID Virus (120 nanometres), without compromising on the breathability of the fabric, and could thus be a powerful tool to prevent the spread of coronavirus and other microbial infections. “We expect that the impact of this innovation on society will be immense and immediate, considering the current situation of the global COVID-19 pandemic,” said Dr Jaiswal. The proposed materials can also be used to fabricate screens/sheets for the creation of makeshift isolation wards, containment cells and quarantines for holding individuals who come in contact with pathogens.
