Near-infrared carbon dot-based platform for bioimaging and photothermal/photodynamic/quaternary ammonium triple synergistic sterilization triggered by single NIR light source

The design of efficient synergistic therapeutic strategies for bacterial infection is highly desirable due to their high therapeutic efficiency and less side effects. In this study, a rapid and effective multi-mode antibacterial platform that integrates quaternary ammonium compounds (QACs), photothermal therapy (PTT) and photodynamic therapy (PDT) was developed. QACs can induce initial damage to the bacterial cell membrane and render it more sensitive to heat. During 808 nm laser irradiation, the generation of hyperthermia and reactive oxygen species (ROS) can induce the death of damaged Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and the corresponding bacterial killing efficiencies are approximately 99.36% and 99.98%, which exceed single-mode therapy. In vivo antibacterial and anti-infective assays proved that effective sterilization could accelerate the infected wound healing process, and the traumas healed well within 14 days after treatment with Cu-RCDs-C35 and 808 nm irradiation. The wound healing area ratio was calculated to be 96%, which substantially exceeds the PBS + Laser, Cu-RCDs, and RCDs-C35+Laser groups. In addition, the cellular imaging experiment showed that Cu-RCDs-C35 could also serve as a fluorescence probe in bioimaging due to its inherent luminescence. Therefore, the present study provides high-efficiency and multifunctional carbon nanomaterials as antibacterial and bioimaging agents.