Molecular design of ultrafiltration membranes with antibacterial properties for the inactivation of antibiotic-resistant bacteria

Ultrafiltration membranes have gained significant prominence in water and wastewater treatment, holding potential for application in combating antibiotic resistance. Herein, we successfully fabricated a polyvinylidene fluoride copolymer-based ultrafiltration membrane capable of effectively removing antibiotic-resistant bacteria (ARB) from water and wastewater through the molecular design approach, incorporating polyionic liquid (PIL) via atom transfer radical polymerization. The as-prepared membrane exhibited bactericidal properties against wild-type bacteria, ARB and opportunistic pathogens, showcasing an inactivation efficiency exceeding 70 %. These properties were attributed to the increased intracellular accumulation of reactive oxygen species and enhanced membrane permeability, suggesting the involvement of oxidative stress and disruption of the cell outer membrane in bacterial cell lysis. To investigate the interaction with bacterial cells, we utilized liposome vesicles as a model, revealing that the PIL brush effectively disrupted the integrity of the bacterial cell's phospholipid bilayer through its alkyl chain. Furthermore, zeta potential measurements indicated that the role of electrostatic interactions between the imidazole ring and bacteria in bacterial inactivation mechanisms. During wastewater filtration, the PIL-M membrane demonstrated outstanding efficiency in total bacteria removal, exceeding 99.1 %. Additionally, the PIL-M membrane displayed significant bacterial inactivation capabilities against total bacteria as well as sulfamethoxazole-resistant bacteria, chloramphenicol-resistant bacteria, and tetracycline-resi8stant bacteria, achieving respective inactivation efficiencies of 91 %, 93 %, 87 %, and 85 %. These results highlight the membrane's potential in mitigating membrane fouling and inactivating antibiotic-resistant bacteria. Overall, the findings of this study suggest that the PIL-M membrane can effectively contribute to controlling bacterial resistance in water and wastewater environments.