Respiratory viruses like SARS-CoV-2 are spread via droplets and short-range aerosols generated when infected people talk, exhale, cough, or sneeze. Face masks are effective in limiting the spread of these viruses. However, most medical-grade and N95 masks are not self-sterilized or reusable, and widespread use of disposable masks demands tremendous manufacturing resources and generates a corresponding amount of waste. Here, we report a novel material for making reusable antimicrobial face masks based on the blown polypropylene filtration media used in medical-grade and N95 masks. We used a facile one-pot method to prepare thin copper@ZIF-8 core-shell nanowires (Cu@ZIF-8 NWs). Thin Cu NWs were stabilized using Pluronic F-127 block copolymer, followed by growth of ZIF-8 to obtain a uniform core-shell structure. The Cu@ZIF-8 NWs were used to functionalize polypropylene-based filtration media by simple dip-coating . The filtration efficiency decreased upon exposure to ethanol (dip-coating solvent) but increased with addition of the nanocomposite, while the hydrophobicity remained constant. The Cu@ZIF-8 NWs showed enhanced antibacterial activity, compared to Cu NWs or ZIF-8 alone, against bacterial strains including S. mutans (Gram-positive) and E. coli (Gram-negative). Up to 91% inhibition of E. coli growth and 86% inhibition of S. mutans growth was observed. Treated filter media exposed to bacteria-laden aerosols also inhibited bacterial growth. Antiviral activity of Cu@ZIF-8 NWs was tested against SARS-CoV2 using virus-infected VeroE6 cells. Adding 1 µg of Cu@ZIF-8 NW per well in a 96-well plate induced 55% inhibition of virus replication after 48 hours. To assess possible effects of human exposure to our material, we evaluated its cytotoxicity against three cell lines and examined its effect on inflammatory response in A549 cells, with favorable results. We demonstrate that Cu@ZIF-8 NWs can functionalize face mask fibers by a simple dip-coating technique, to impart antimicrobial properties through sustained Cu and Zn ion release. The proposed low-cost and scalable synthesis strategy of Cu@ZIF-8 NWs provides great potential for application of these materials in reusable facemasks and other medical textiles.

Supriya Mahajan

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