Antimicrobial Personal Protection Clothing: Development of Visible Light Activated Antimicrobial Coatings for Nonwoven Polypropylene Fibers

During the COVID-19 pandemic, the use of polypropylene fleece-based personal protection equipment (PPE) increased significantly to over ten million tons. Typically, most PPEs are discarded after a single use, to prevent self-infection of users and spread of infectious agents. However, in order to minimize plastic waste without compromising the protective properties of PPE, it is crucial to explore new reusable or longer-lived materials. Here, a visible light-activatable antimicrobial photodynamic dye coating for PPEs is presented. In this context, coating with thiomorpholino-methylene blue (TMB), derived from methylene blue by introducing two thiomorpholine units, is found to show high antibacterial activity. TMB is integrated into rotary printing suspension, a commercial nitrocellulose-based printing matrix. The concentration of TMB in adhesive is optimized, and found that 5% TMB is suitable for coating PPE, for reducing the number of Gram-positive and -negative bacteria by 99.99% after 6 h of white light irradiation. Bacterial filtration efficiency and breathability tested according to EN 14683, confirmed that TMB coating does not affect the filter performance. Thus, this antimicrobial photodynamic dye coating technique offers a promising solution for a safer and extended use of PPE, and reduction of plastic waste generated by PPEs. A versatile antimicrobial photodynamic coating for nonwoven polypropylene fleece is presented here. Thiomorpholino-methylene blue proved to be a highly effective photosensitizer in producing singlet oxygen under visible light irradiation, and suitable for industrial rotary printing with nitrocellulose-based adhesive. The coating on the surface of personal protection equipment, for example, surgical masks, reduced the growth of Gram-negative and -positive bacteria by over 99.99 %.image