Fig. 1

Characteristics of scaffolds. (a) ¹ H-NMR spectrum of GelMA: the methacrylation of gelatin was showed by dashed line in the spectrum of GelMA. (b) FT-IR spectra of fragmented ESM fibers (EMF), GelMA hydrogel (GM), GM/EMF hydrogel, GM/EMF/P hydrogel, and propolis