Layer-Restacked 3D Ti3C2 Nanostructures with Efficient Photothermal Antibacterial Activities

Multidrug-resistant bacterial infections have emerged as a global public health crisis due to antibiotic misuse. In this study, we develop a layer-restacked 3D Ti3C2 nanostructure utilizing ice-templating. This nanostructure exhibits outstanding hydrophilicity, biocompatibility, and stability, as well as enhanced absorption, extinction coefficient, and photothermal conversion efficiency. Additionally, the layer-restacked 3D Ti3C2 nanostructure demonstrates excellent antibacterial activity against MDR Escherichia coli and MDR Staphylococcus aureus irradiated by 808 nm near-infrared light (NIR). Specifically, the mechanism of photothermal action against multidrug-resistant bacteria involves structural damage to the bacterial membranes, leading to the leakage of bacterial contents after layer-restacked 3D Ti3C2 nanostructures adhered under NIR irradiation. The results of transcriptome analysis show that the 3D Ti3C2 nanostructure regulates the membrane transporters and membrane transporter proteins on the bacterial cell membrane as well as the activities of enzymes associated with them, which in turn affect the metabolic processes of organic acids and other organic substances in the bacterial cell. The DNA-binding transcriptional activator EvgA is significantly downregulated, which may play a crucial role in inhibiting the emergence of drug resistance in bacteria when exposed to the layer-restacked 3D Ti3C2 nanostructure. The layer-restacked 3D Ti3C2 nanostructure is an effective photothermal antimicrobial nanostructure against multidrug-resistant bacteria.