Metal-organic framework based nanozyme hybrid for synergistic bacterial eradication by lysozyme and light-triggered carvacrol release

Pathogenic bacteria seriously endanger human health. Metal-organic framework (MOF)-enzyme composites are novel antibacterial materials for effective bacterial inactivation. In this study, we develop a MOF-based nanozyme hybrid for synergistic bacterial eradication, which integrates features of bacterial capture, magnetic assembly, lysozyme hydrolysis, and light-triggered thermal generation and carvacrol release. Core-shell nanoparticles (Fe3O4@[email protected]2-MIL-88B(Fe), FPM; PVP = polyvinylpyrrolidone) are synthesized by loading PVP-modified Fe3O4 to NH2-MIL-88B(Fe), and then covalently immobilizing lysozyme onto the FPM surface through enzymatic reaction by microbial transglutaminase. The lysozyme-covered FPM is further employed as a host matrix for loading antibacterial carvacrol to synthesize Fe3O4@[email protected](Fe)–NH-lysozyme/carvacrol (FPMLC) nanozyme hybrid. This FPMLC can capture bacteria by electrostatic attraction and the FPMLC-bacteria composite is then assembled by an extra magnet. The lysozyme layer can degrade peptidoglycan of the bacterial cell wall, and the released carvacrol can disrupt the bacterial cell membrane under near-infrared (NIR) irradiation. Systematic antibacterial results demonstrate that the developed FPMLC nanozyme hybrid at a low dose of 100 μg/mL completely inactivates (100%) both Escherichia coli and Staphylococcus aureus at cell density of 106 CFU/mL. This FPMLC exhibits high-efficiency antibacterial efficacy but no significant cytotoxicity in vitro, and therefore provides promising antibacterial applications in biomedical, environmental, and food fields.