Photothermal activated Ni@ZIF-C nanocatalyst boosts triple-mode therapy of skin scaffold against bacterial and biofilm infections

Bacterial infections especially bacterial biofilm infections have always been a major obstacle to the reconstruction of deep skin defects. Herein, a photothermal activated multifunctional nanocatalyst (Ni@ZIF-C) is synthesized by doping Ni into zeolitic imidazolate framework-67 (ZIF-67) and carbonizing, following by introducing into polycaprolactone (PCL) to prepare porous scaffolds by selective laser sintering. Especially, the Ni@ZIF-C nanocatalyst endows scaffold favorable chemo/photodynamic/photothermal triple-mode antibacterial activity under near-infrared light irradiation. On the one hand, the highly conductive Ni@ZIF-C improves the separation efficiency of photogenerated electron-hole pairs to trigger reactive oxygen species (ROS) generation, achieving photodynamic sterilization. On the other hand, the superior photothermal conversion efficiency of Ni@ZIF-C in scaffold not only directly destruct bacterial biofilms by hyperthermia but also enhance its own peroxidase-like activity to induce more ROS production, and the latter is bactericidal by chemical mode. Importantly, the destruction of the biofilms enables the pre-generated ROS to kill deep bacteria, achieving a triple-mode combined or even synergistic antibacterial efficacy. Results demonstrated that the PCL/Ni@ZIF-C scaffold with triple bactericidal modalities presents stronger bactericidal ability than PCL/ZIF-67 and PCL scaffolds. Encouragingly, it remarkably destroyed S. aureus and E. coli biofilms and inhibited biofilm formation, effectively triggered massive ROS generation and ultimately eradicated the bacteria deep within the biofilms. Taken together, the scaffold exhibited tremendous potential in utilizing photothermal activated multimodal combined antibiofilm and antibacterial therapy.