On-demand removable hydrogels based on photolabile cross-linkings as wound dressing materials.

Because of their complex and evolving characteristics, burn wounds always need repeated treatments to gradually and specifically re-expose the wound for further care, which cause pain to patients and reinjury to newly formed tissues. Thus, it is highly desirable to remove wound dressings in a controllable, painless, noninvasive, and facile way. Herein, we synthesized a photocleavable polyethylene glycol (PEG) crosslinker, and prepared a series of hydrogels by mixing this cross-linker with glycol chitosan (GC) in different ratios. In situ gelation occurred within 2 min, which was beneficial for hydrogels to be injected to the wound site and cover irregular shapes. The hydrogels were destroyed upon exposure to UVA light, which was noninvasive and could spatiotemporally control their breakdown, leading to the on-demand, noninvasive, and controllable removal of the hydrogels. The hydrogels also showed good swelling, suitable mechanical properties and adhesive strength. Moreover, the cytotoxicity assay demonstrated the good cytocompatibility of the precursors and degradation products. This photo-triggered on-demand removal will provide a promising method to alleviate pain during dressing change and facilitate future wound care.