Facile and green synthesis of decatungstate-based nickel(ii) complex coated onto modified Fe3O4 nanoparticles with enhanced antimicrobial activity against antibiotic-resistant bacteria

Abstract

Because indiscriminate antibiotic usage has driven bacterial evolutionary selection so that there is increasing microbial resistance, there is an urgent need to develop new generations of effective antibacterial agents. Herein, we developed a facile and green strategy for the preparation of a nanostructured Fe₃O₄@PDA@Ni-DT composite by anchoring decatungstate-based nickel(II) complex (Ni-DT) ([Ni(HL)₂]₂[W₁₀O₃₂]·4H₂O, HL = 2-acetylpyridine thiosemicarbazone) onto hybrid Fe₃O₄@PDA (PDA = polydopamine) nanosheets. Compared with pristine Ni-DT and Fe₃O₄@PDA, the Fe₃O₄@PDA@Ni-DT composite killed 99.3% of Gram-negative Escherichia coli and 98.8% of Gram-positive Staphylococcus aureus bacteria. Notably, the composite showed potent antibacterial activity against antibiotic-resistant E. coli bacteria (ampicillin and kanamycin). The composite retained excellent recyclable performance due to the introduction of Fe₃O₄ nanoparticles. The detailed antibacterial mechanism used by the hybrid Fe₃O₄@PDA@Ni-DT composite against E. coli indicates that the nanostructured composite played a significant role in destroying the cell membrane of bacteria, inhibiting the enzymatic activity of bacteria, and increasing bacteria-destroying oxidative stress. The current work provides an effective strategy to synthesize multifunctional decatungstate-based material for highly effective and reusable antimicrobial agents.