Advancing NIR-II Photothermal Antibacterial Capability of Polydopamine Nanoparticles through Iron-Doped Molybdenum Oxide Functionalization

Polydopamine (PDA) exhibits admirable photothermal properties and biocompatibility for biomedical applications; however, its near-infrared (NIR-II) absorption and antibacterial performance remain insufficient. Herein, we introduced Fe-doped molybdenum oxide (MoFeO x ) functionalized PDA composites exhibiting robust NIR absorption, reactive oxygen species (ROS) generation, and glutathione (GSH) depletion, thereby achieving a synergistic photothermal therapy/chemodynamic antibacterial effect. Polyethylenimine (PEI) served as the interlayer to bind MoFeO x onto the surface of PDA through electrostatic interaction. Compared with pure PDA, the nanoparticles demonstrated a 145% improvement in photothermal efficiency in the NIR-II range (1064 nm) when incorporating only 2.2% MoFeO x . This was attributed to the generation of electron “donor” and “acceptor” within the material, resulting in a reduction in the energy band gap and enhanced electron migration, as characterized by ultraviolet photoelectron spectroscopy (UPS). The nanoparticles exhibited synergistic therapeutic effects on E . coli and S . aureus through photothermal/chemodynamic therapy. This work offers an alternative methodology for improving the photothermal performance of PDA and designing synergistic antibacterial materials.