Anti-viral, anti-bacterial, but non-cytotoxic nanocoating for reusable face mask with efficient filtration, breathability, and robustness in humid environment

We fabricated a multi-use face mask with anti-bacterial and anti-viral, but non-cytotoxic properties by adding a functional nanocoating on an electrospun nanofiber filter. The nanocoating consists of a copolymer synthesized from dimethyaminomethyl styrene (DMAMS) monomer containing anti-microbial tertiary amine moiety, and a biocompatible crosslinker, ethylene glycol dimethylacrylate (EGDMA). Initiated chemical vapor deposition process is utilized to deposit the nanocoating in order to impart desired functionalities conformally onto the nanofiber filter without deforming its highly porous structure. The synthesized non-cytotoxic copolymer of p(DMAMS-co-EGDMA), or pDE film showed excellent biocidal efficacy of > 99.995% and > 99.985% against Escherichia coli O157: H7 (E. coli O157: H7) and Staphylococcus aureus, respectively. The pDE-coated nanofiber filter shows a filtration efficiency of 91% with extremely low air resistance of ∼ 50 Pa. In highly humid conditions, the pDE-coated nanofiber filter shows long-term anti-microbial efficacy of 99.89% for E. coli O157: H7 up to 168 h, 99.21%, and 99.23% for human influenza virus (H1N1) strain A/Puerto Rico/8/1934 and human beta-coronavirus strain OC43 up to 100 h, without sacrificing breathability, and filtration performance. Furthermore, the surface-modified filter can easily eliminate dead pathogens with a simple water rinse, which enabled the full retention of the filtration efficiency even in six washing cycles, proving excellent reusability. We envision the highly breathable, antimicrobial, multi-use face mask will serve as an environmentally free platform for personal protective equipment against future viral threats.