Rapid and highly effective bacteria-killing by polydopamine/IR780@MnO2-Ti using near-infrared light

Bacterial infections are becoming a serious public health challenge because the abuse of antibiotics worldwide has caused bacterial resistance and the occurrence of superbugs. In this work, a new near-infrared (NIR) photoresponsive coating was constructed on Ti implant material, which was composed of MnO2, IR780 photo sensitizer and polydopamine (PDA). Under the irradiation of 808 nm NIR light, the component of MnO2 in the coating exhibited high photothermal performance, and IR780 could be stimulated to generate ROS as a photosensitizer. The addition of PDA not only improved the cytocompatibility of the composite coating but also strengthened the light absorption ability of the system. Under the irradiation of 808 nm NIR light for 15 min, the composite coating killed 99.94% Staphylococcus aureus and 99.89% Escherichia coli on Ti plates. This rapid and highly effective bactericidal rate was ascribed to the synergistic effects of photothermal performance and photodynamic effect of the coatings excited by NIR light. Cell culture tests showed that PDA/IR780@MnO2-Ti had good cytocompatibility due to the excellent biocompatibility of PDA and nanostructured surface. Therefore, this surface system will be a very promising plateform to safely and effectively kill bacteria on biomedical devices and implants in a short time.