Antimicrobial foam-filter based on commercial support coated with polydopamine and silver nanoparticles for water treatment

Fresh water is a critical resource on the planet and the treatment techniques employed worldwide are often insufficient at removing contaminants, leading to their release in the environment. This work displays the development of a foam-filter based on open-cell polyurethane foams coated with polydopamine and an antimicrobial metal for water treatment processes. A simple coating method is proposed and the resulting tool is characterized. Its antimicrobial activity is assessed on pure water-based cultures of Staphylococcus aureus, Escherichia coli, Legionella pneumophila and Candida albicans in optimal growth conditions. This study also investigates the stability and reusability of the foam-filter. The results show that silver grafting via this one-step original approach (namely OCPUF@PDA/Ag) exhibits a good antimicrobial activity on the selected microorganisms, with a complete microbicidal effect against C. albicans and E. coli after 3 h of contact time (5 and 6 Log decrease, respectively), and after 24 h of contact time for S. aureus. The foam-filter shows great stability and recyclability as it can be reused at least 4 times with the same overall activity, as well as significant antifouling properties. The mechanism of action was partially investigated and shows that reactive oxygen species are generated inside the bacterial cells after contact with the foam. This study gives a starting framework for the development of a bio-inspired polydopamine material with interesting physical, antifouling and antimicrobial properties applicable in water treatment processes.