ROS-driven antibacterial mechanisms of multi-metallic (TiVNbMo)₄C₃T_x MXene

Multi-metallic MXenes such as entropy-stabilized (TiVNbMo)₄C₃T_x exhibit synergistic electronic and redox properties beyond those of monometallic MXenes, yet their antibacterial behavior in aqueous environments remains poorly understood. In particular, how multi-elemental composition influences bactericidal mechanisms has not been elucidated. Here, we investigate how multi-metallic composition governs the antibacterial performance of (TiVNbMo)₄C₃Tₓ MXenes in direct comparison with monometallic Ti₃C₂T_x and Nb₂CT_x. This work links material structure to ROS generation and membrane disruption, providing a mechanistic basis for MXene design. Concentration-dependent colony-forming unit (CFU) assays against Escherichia coli and Staphylococcus aureus revealed that (TiVNbMo)₄C₃T_x achieved > 98% bacterial viability loss within 4 h at 100–200 μg/mL. Scanning and transmission electron microscopy showed membrane rupture consistent with a nanoknife effect. Furthermore, oxidative-stress analysis by abiotic assays demonstrated that (TiVNbMo)₄C₃T_x generates stronger oxidative stress, superoxide (O₂•⁻), and hydroxyl radicals (•OH) than Ti₃C₂T_x and Nb₂CT_x. Moreover, monometallic MXenes exhibited measurable antibacterial activity; however, the larger-flake, multi-metallic MXene demonstrated superior killing efficiency, particularly at low concentrations, where ROS generation dominated and the nanoknife-like physical effect served as a secondary contribution. These findings confirm that (TiVNbMo)₄C₃T_x enhances both ROS-mediated and physical antibacterial activity. (Figure presented.)