Multilayered Upconversion\nNanocomposite-Based Photodynamic\nHydrogel Dressings for Wound Sterilizing and Healing

Abstract

Skin wounds are particularly susceptible to bacterial\ninfection,\nwhich seriously affects skin healing. Therefore, wound dressing with\nantibacterial properties is urgently needed for skin trauma treatment.\nHere, we have designed a hydrogel dressing by utilizing a multilayered\nupconversion nanocomposite that is constructed by the upconversion\nnanoparticles (UCNPs) coated with a mesoporous silica-loaded zinc\nphthalocyanine (ZnPc) photosensitizer. The nanocomposite can produce\nsinglet oxygen for photodynamic therapy under 980 nm excitation by\nluminescent energy resonance transfer between UCNPs and ZnPc, which\nendows the antibacterial activity during the wound healing process.\nFurthermore, by utilizing the non-toxic active ester of polyethylene\nglycol as the cross-linking agent, the nanocomposite is assembled\nin chitosan to generate the hydrogel dressing, whereas chitosan is\nconsidered an ideal material for promoting wound healing. The experiments\nshow that the dressing has good antimicrobial activity against Staphylococcus aureus and Escherichia\ncoli. Meanwhile, in vivo experiments demonstrate that\nthe antibacterial hydrogel dressing can effectively reduce inflammation\nand significantly accelerate wound healing due to its low toxicity,\ndeep tissue penetration, good biocompatibility, and strong antibacterial\ncapacity. Such a photodynamic hydrogel dressing designed here would\nprovide a practical application pathway for photodynamic sterilization\nand treating emergencies as a total solution.