Engineering of Materials for Respiratory Protection: Salt-Coated Antimicrobial Fabrics for Their Application in Respiratory Devices

ConspectusThe development of a highly effective, low-cost method for protection against direct transmission through infectious media associated with respiratory diseases has been considered to be a major challenge in the management of the pandemic outbreak. Currently, filtration in respirators and masks depends on the mesh size, raising safety concerns about direct contact with the virus-laden layers of masks and respirators during use and disposal. Also, conventional medical face masks and respirators are recommended for single use only because long-term use and reuse of masks increase the risk of contact transmission of pathogens. As a result, mask reusability has gained much attention in addressing the global problem of respirator and mask shortages during the COVID-19 pandemic. Furthermore, coinfection by influenza, SARS-CoV-2, and bacteria has been an ongoing issue in the current COVID-19 pandemic. In our response to the increasing demand for more convenient forms of disease control, our group has investigated antimicrobial technologies for respiratory devices against pandemic/epidemic diseases and developed two universal antimicrobial coating technologies: (1) nonwashable, reusable salt-coated fabrics and (2) washable, photopolymerizable polymer-coated fabrics which efficiently inactivate infectious viruses by contact with the filter. This is an opportune time to assess research efforts toward antimicrobial face mask technology for its expected impact on society and the economy.In this Account, we introduce the importance of respiratory devices for protection against respiratory diseases, decontamination methods, technical challenges for reuse and extended use, antimicrobial substances used in masks, antimicrobial functionalization strategies for mask fibers, and the characterization of antimicrobial performance and the limitations of the current procedure. Then, the major focus will be directed to discussing the continued efforts of our group to develop antimicrobial fabrics for face mask covers and face masks/respirators based on salt-coated polypropylene (PP) fibers. In the following sections of this Account, we will first discuss salt coating methods and pathogen inactivation mechanisms in salt-coated filters. Then, an overview of our recent progress in evaluating the antimicrobial performance of salt-coated PP fabrics against five different bacterial species, influenza viruses, and human coronaviruses will be presented. The technical challenges in the implementation of the technology will be highlighted in the last section. We believe that easy-to-implement antimicrobial respiratory devices would guarantee improved protection without decontamination processes and enable rapid responses to future pandemic/epidemic outbreaks.