Copper-Cysteine Nanostructures for Synergetic Photothermal Therapy and Chemodynamic Therapy of Bacterial Skin Abscesses

Skin lesions, including skin bacterial abscesses, have become one of the most important health challenges and usually need systemic high-dose antibiotics. Therefore, it is of particular importance to develop novel approaches for treating this ever-growing challenge to human health. To address this challenge, herein a copper nanostructure is developed giving combined photothermal and chemodynamic therapies for focal infection treatment. The Cu-based nanostructures with intrinsic catalytic properties are prepared by D-L or L cysteine (Cys) as ligand and copper ions. It is shown that the multifunctional copper-Cys (Cu-Cys) nanostructures can produce reactive oxygen species (ROS) and they exhibit near infrared (NIR)-enhanced catalytic activities to improve ROS production for highly efficient eradication of bacteria. Moreover, the results proved O₂ evolution property of the Cu-Cys nanoparticles (NPs). The nanostructures show shape-dependent antibacterial activity where DL-Cu-Cys NPs show higher bactericidal performance than L-Cu-Cys NPs. In vitro results demonstrate that 2.5 and 1.25 µg mL⁻¹ of DL-Cu-Cys NPs is enough to achieve rapid killing of Escherichia coli (E. coli) or Staphylococcus aureus (S. aureus) respectively under 808 nm light irradiation in 10 min. This work introduces a unique photoactive nanoagent to efficiently treat subcutaneous abscess by combining NIR light-triggered photothermal effect and catalytic generation of ROS without using any antibiotic.