Fe-Chelated Polydopamine Nanoparticles Prepared through Photo-Fenton Reaction for Combined Photothermal/Chemodynamic Antibacterial Therapy

Due to its tunable degradation kinetics, broad-spectrum light absorption and biocompatibility, polydopamine (PDA) has emerged as a promising candidate for photothermal therapy. However, the photothermal conversion efficiency of PDA within the near-infrared spectral range is suboptimal. To address this issue, we synthesized PDA via a photo-Fenton reaction under neutral conditions. In this system, dopamine and Fe³⁺ form bis-ligand complexes, enhancing iron content in the nanoparticles. Light irradiation accelerates electron transfer from ligands to Fe³⁺, speeding up PDA generation. The nanoparticles, named PDA-7.4-Fe-L NPs, exhibited a substantial improvement in photothermal conversion efficiency, reaching 52.24% under 808 nm laser irradiation. Notably, at a remarkably low concentration of 20 μg/mL, PDA-7.4-Fe-L NPs achieved exceptional antibacterial rates (>99.99%) against Gram-negative E. coli and Gram-positive S. aureus within 10 min. The cytotoxicity results confirm that PDA-7.4-Fe-L NPs exhibit excellent biocompatibility. The remarkable antibacterial efficacy and biocompatibility of PDA-7.4-Fe-L NPs make it a potential antibacterial agent.