Preparation of Au/RuO2 multifunctional nanocomposite and its application in chemodynamic-photothermal synergistic antibacterial.

Food safety and public health are severely compromised by foodborne pathogens such as Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Nevertheless, there are still significant challenges in developing effective and stable antibacterial approaches. Herein, an Au/RuO2 nanocomposite with a clear and well-defined core-shell structure was synthesized via an one-step hydrothermal by tuning the Au and Ru precursor contents. Benefiting from its exceptional peroxidase-like (POD-like) activity (Km: 0.15 mM for TMB, 5.68 mM for H2O2) and high photothermal conversion efficiency (85.39%), the nanocomposite was used in antibacterial purposes. The results demonstrated that at a low concentration of 2.88 µg/mL, complete killing of S. aureus and E. coli was achieved via the generation of reactive oxygen species (ROS) (hydroxyl radicals (·OH) and singlet oxygen (1O2)), localized temperature elevation, biofilm suppression and biofilm eradication. The antibacterial performance was markedly superior to that of single-agent treatments (H2O2 or 808 nm laser alone, requiring ~ 11.54 µg/mL), underscoring its broad-spectrum and highly efficient chemodynamic-photothermal (CDT-PTT) synergistic antibacterial potential. Moreover, the Au/RuO2 nanocomposite also exhibited excellent stability (could maintain its original activity after 90 days of storage at 4 °C and 20 days at room temperature), good reusability (could retain over 90% of its original activity after five cycles) and high biocompatibility (no toxicity to multiple cells at 100 µg/mL, and with a hemolysis rate below 2%), which made it a potential material for efficient and safe antibacterial applications. In summary, the Au/RuO2 nanocomposite exhibited excellent and stable POD-like activity, photothermal properties, synergistic antibacterial effects and biocompatibility, which not only enrich the family of multifunctional nanomaterials but also offer a promising candidate for antibiotic-free antibacterial strategies.