Magnetism and NIR dual-response polypyrrole-coated Fe₃O₄ nanoparticles for bacteria removal and inactivation

Microbial contamination of water represents a great threat to the public health that has attracted worldwide attention. In this work, polypyrrole magnetic nanoparticles (Fe₃O₄@PPy NPs) with sterilization properties were fabricated. More specifically, the Fe₃O₄@PPy NPs obtained via aqueous dispersion polymerization and an in situ chemical oxidative polymerization exhibited a cationic surface and high photothermal conversion efficiency. More than 50% of bacteria adsorption can be achieved at a dosage of 100 μg/mL Fe₃O₄@PPy NPs under magnetic field, and high photothermal sterilization efficacy (~100%) can be obtained upon NIR exposure at the same dosage for 10 min. Noteworthy, the Fe₃O₄@PPy NPs can be recycled by magnetism and reused without affecting their photothermal sterilization capability. This study clearly provides experimental evidence of the great potential of Fe₃O₄@PPy NPs as stable and reusable nanocomposite materials for bacteria adsorption and photothermal sterilization performance. The application of Fe₃O₄@PPy NPs can realize enviromental-friendly bacterial contaminated water treatment as well as provide stratgies for synergistical antibacterial materials design.