Rapid bacteria trapping and killing of metal-organic frameworks strengthened photo-responsive hydrogel for rapid tissue repair of bacterial infected wounds

During the wound healing process, it is necessary to protect the tissue from bacterial infections and other external damage in environment. Functional artificial hydrogels as suitable wound dressings to act as barriers have attracted more and more attention. In the study described herein, quaternary ammonium and double-bond modified chitosan and metal–organic framework (MOF) particles (Prussian blue nanoparticles [PBNPs]) were used to synthesize photosensitive hydrogels through free radical polymerization. The synthesized hydrogels exhibited excellent photothermal properties under 808 nm near-infrared (NIR) light irradiation due to the existence of PBNPs, which could absorb NIR light and produce light due to the charge transfer between Fe³⁺ and Fe²⁺ in the structure. The hydrogels can capture the bacteria tightly by electrostatic absorption. During this course, the normal metabolism of bacteria was inhibited due to the perturbation of the surface potential of the bacterial membrane and the subsequent inhibition of bacterial respiration, which led to the highly effective, rapid killing of bacteria together with the synergistic action of photothermal effects. The antibacterial ratio of the hydrogels could reach up to 99.97% and 99.93% against Staphylococcus aureus and Escherichia coli, respectively. Furthermore, PBNPs particles were also able to strengthen the mechanical property of the hydrogel through the interfacial interaction between the chitosan polymer and the PBNPs. The synthesized hydrogels also showed good in vitro biocompatibility and excellent in vivo antibacterial properties with no damage to the major organs. Thus, the synthesized hydrogels have great potential as a safe and efficient wound dressing.