Disrupting biofilm and eradicating bacteria by Ag-Fe₃O₄@MoS₂ MNPs nanocomposite carrying enzyme and antibiotics

In this study, novel multilayered magnetic nanoparticles (ML-MNPs) loaded with DNase and/or vancomycin (Vanc) were fabricated for eliminating multispecies biofilms. Iron-oxide MNPs (IO-core) (500–800 nm) were synthesized via co-precipitation; further, the IO-core was coated with heavy-metal-based layers (Ag and MoS₂ NPs) using solvent evaporation. DNase and Vanc were loaded onto the outermost layer of the ML-MNP formed by nanoporous MoS₂ NPs through physical deposition and adsorption. The biofilms of S. mutans or E. faecalis (or both) were formed in a brain-heart-infusion broth (BHI) for 3 days, followed by treatment with ML-MNPs for 24 h. The results revealed that coatings of Ag (200 nm) and ultrasmall MoS₂ (20 nm) were assembled as outer layers of ML-MNPs successfully, and they formed Ag-Fe₃O₄@MoS₂ MNPs (3–5 μm). The DNase-Vanc-loaded MNPs caused nanochannels digging and resulted in the enhanced penetration of MNPs towards the bottom layers of biofilm, which resulted in a decrease in the thickness of the 72-h biofilm from 48 to 58 μm to 0–4 μm. The sustained release of Vanc caused a synergistic bacterial killing up to 96%–100%. The heavy-metal-based layers of MNPs act as nanozymes to interfere with bacterial metabolism and proliferation, which adversely affects biofilm integrity. Further, loading DNase/Vanc onto the nanoporous-MoS₂-layer of ML-MNPs promoted nanochannel creation through the biofilm. Therefore, DNase-and Vanc-loaded ML-MNPs exhibited potent effects on biofilm disruption and bacterial killing.