A polyoxometalate-modified magnetic nanocomposite: a promising antibacterial material for water treatment

In this work, polyoxometalate-modified magnetic nanocomposite Fe₃O₄@PDA@POM was prepared by coating [Cu(HL)₄]₂[P₂Mo₅O₂₃]₂·8H₂O (POM, L = 2-aminopyridine) on the surface of a preassembled polydopamine (PDA)-capped carboxyl-functionalized Fe₃O₄ magnetic microspheres. Our studies on Gram negative bacterium Escherichia coli (E. coli) indicated that owing to the collective effect between preassembled Fe₃O₄ and POM, the Fe₃O₄@PDA@POM nanocomposite loaded on nickel foam exhibited outstanding antibacterial activity and reusability, and even after 6 cycles it has a high antibacterial capability of ca. 90%. Further extension of this investigation towards Gram positive bacterium Staphylococcus albus (S. aureus) demonstrated a similar toxicity pattern, confirming the potential applications of this material for water treatment in biochemical processes. The antibacterial mechanism of the Fe₃O₄@PDA@POM nanocomposite was further investigated by taking E. coli as a model microorganism.