Silk fibroin-gelatin photo-crosslinked 3D-bioprinted hydrogel with MOF-methylene blue nanoparticles for infected wound healing.

Photo-crosslinked hydrogel (PH) is an outstanding candidate for three-dimensional (3D) printing as a wound dressing because of its high efficiency in crosslinking and injectability. In this study, methylene blue (MB)-loaded UiO-66(Ce) nanoparticles (NPs) were synthesized to prevent drug self-aggregation and achieve the photodynamic therapy (PDT) effect for efficient antibacterial action. Then, a composite photocrosslinked silk fibroin (SF)/gelatin hydrogel loaded with MB@UiO-66(Ce) NPs (MB@UiO-66(Ce)/PH) was fabricated. The printability and the improvement of the mechanical properties of the hydrogel by the NPs were clarified. The hydrogel exhibited good biocompatibility and promoted the migration and proliferation of fibroblasts. With the PDT effect of MB@UiO-66(Ce) NPs, the hydrogel showed an excellent antibacterial effect, which became more pronounced as the concentration increased. In vivo study showed that the MB@UiO-66(Ce)/PH could fill the defects without gaps and accelerate the repair rate of full-thickness skin defects in mice. The MB@UiO-66(Ce)/PH with antibacterial properties and tissue healing-promoting ability provides a new strategy involving 3D bioprinting for preparing wound dressings.