Polycationic Cotton Filters for Bacterial Capture and Inactivation in Water and Air

Bacterial pathogens pose a significant global health challenge. While filtration systems can effectively disinfect water, clogging and resistance to flow from small pore sizes in the micrometer range often hinder their performance. This study presents the antimicrobial functionalization of cotton fabrics for water and air disinfection. Cotton fabrics with a mesh size of around 200 µm are covalently functionalized with the polycation [2-(Methacryloyloxy) ethyl] trimethylammonium chloride (METAC) using a scalable water-based coating/drying and photopolymerization process. Chemical and structural analyses, conducted using confocal Raman microscopy and mass spectrometry, confirm the stable covalent binding of METAC to cotton fibers. Filtration assays in a specifically designed flow-through setup demonstrate that the METAC-coated filters achieve > 5 log reductions of Escherichia coli and Staphylococcus aureus in the effluent. The bacterial cells are neutralized upon contact with the METAC-coated surfaces in wet and dry conditions. The antimicrobial activity of the filters against microorganisms in native river water is also demonstrated, underscoring their potential for applications. The findings contribute to the understanding of antimicrobial materials and can guide the development of advanced water and air filtration materials to combat bacterial infections effectively.