Argon plasma-modified bacterial cellulose filters for protection against respiratory pathogens

Due to the global spread of the SARS-CoV-2 virus and the resultant pandemic, there has been a major surge in the demand for surgical masks, respirators, and other air filtration devices. Unfortunately, the fact that these filters are made of petrochemical-derived, non-biodegradable polymers means that the surge in production has also led to a surge in plastic waste. In this work, we present novel, sustainable filters based on bacterial cellulose (BC) functionalized with low-pressure argon plasma (LPP-Ar). The “green” production process involved BC biosynthesis by Komagataeibacter xylinus, followed by simple purification, homogenization, lyophilization, and finally LPP-Ar treatment. The obtained LPP-Ar-functionalized BC-based material (LPP-Ar-BC-bM) showed excellent antimicrobial and antiviral properties, with no cytotoxicity versus murine fibroblasts in vitro. Further, filters consisting of three layers of LPP-Ar-BC-bM had >99% bacterial and viral filtration efficiency, while maintaining sufficiently low airflow resistance (6 mbar at an airflow of 95 L/min). Finally, as a proof-of-concept, we were able to prepare 80 masks with LPP-Ar-BC-bM filter and ~85% of volunteer medical staff assessed them as good or very good in terms of comfort. We conclude that our novel sustainable, biobased, biodegradable filters are suitable for respiratory personal protective equipment (PPE), such as surgical masks and respirators. Further, with scale-up, they may be adapted for indoor air handling filtration in hospitals or schools.