The fluorescence imaging and precise suppression of bacterial infections in chronic wounds by porphyrin-based metal-organic framework nanorods.

Nano-antibacterial agents can play a critical role in chronic wound management. However, the design of an intelligent nanosystem that can provide both a visual warning of infection and precise sterilization remains a hurdle. Herein, a rod-like porphyrin-based metal-organic framework theranostic nanosystem (Zn-TCPP nanorods) is fabricated via coordination chelation between tetrakis(4-carboxylphenyl)porphyrin and zinc ions. This system can show significant fluorescence activation in response to the local elevated pH shown by chronic wounds, a main indicator of wound infection. Meanwhile, under the guidance of fluorescence imaging, the highly spatiotemporally precise photodynamic inactivation of microorganisms can be carried out without the destruction of surrounding normal cells and nascent cells. The results demonstrated that the Zn-TCPP nanorods were a highly sensitive and reversible probe for sensing alkaline pH levels. Alterations in the fluorescence of the Zn-TCPP nanorods can accurately indicate the infection status and heterogeneity of infection within the wound bed. Under specific light irradiation, the Zn-TCPP nanorods can exterminate 97% of Staphylococcus aureus via the generation of reactive oxygen species (ROS). Assays of extensive wounds demonstrate that the precise fluorescence-imaging-guided suppression of bacterial infection can significantly reduce the mouse mortality rate and accelerate wound healing. This system provides the opportunity for "precision medicine" relating to chronic wounds and some large-area wounds.