Multilayered Upconversion Nanocomposite-Based Photodynamic Hydrogel Dressings for Wound Sterilizing and Healing

Skin wounds are particularly susceptible to bacterialinfection,which seriously affects skin healing. Therefore, wound dressing withantibacterial properties is urgently needed for skin trauma treatment.Here, we have designed a hydrogel dressing by utilizing a multilayeredupconversion nanocomposite that is constructed by the upconversionnanoparticles (UCNPs) coated with a mesoporous silica-loaded zincphthalocyanine (ZnPc) photosensitizer. The nanocomposite can producesinglet oxygen for photodynamic therapy under 980 nm excitation byluminescent energy resonance transfer between UCNPs and ZnPc, whichendows the antibacterial activity during the wound healing process.Furthermore, by utilizing the non-toxic active ester of polyethyleneglycol as the cross-linking agent, the nanocomposite is assembledin chitosan to generate the hydrogel dressing, whereas chitosan isconsidered an ideal material for promoting wound healing. The experimentsshow that the dressing has good antimicrobial activity against Staphylococcus aureus and Escherichiacoli. Meanwhile, in vivo experiments demonstrate thatthe antibacterial hydrogel dressing can effectively reduce inflammationand significantly accelerate wound healing due to its low toxicity,deep tissue penetration, good biocompatibility, and strong antibacterialcapacity. Such a photodynamic hydrogel dressing designed here wouldprovide a practical application pathway for photodynamic sterilizationand treating emergencies as a total solution.

Automated summary

A hydrogel dressing with antibacterial properties was designed using a multilayered upconversion nanocomposite consisting of upconversion nanoparticles coated with a mesoporous silica-loaded zinc phthalocyanine photosensitizer. The nanocomposite exhibited antibacterial activity through photodynamic therapy. The dressing, assembled with chitosan using a non-toxic active ester of polyethylene glycol as the cross-linking agent, showed good antimicrobial activity and significantly accelerated wound healing in vivo due to its low toxicity, deep tissue penetration, good biocompatibility, and strong antibacterial capacity. This photodynamic hydrogel dressing provides a practical application pathway for sterilization and wound treatment.