Biocompatibility of silk methacrylate/gelatin-methacryloyl composite hydrogel and its feasibility as a vascular tissue engineering scaffold

Silk methacrylate (SilMA) has been studied extensively due to its ability to modify Silk fibroin (SF) by increasing the water solubility and enhancing the mechanical properties of SF hydrogels. However, SilMA hydrogels are generally soft with weak mechanical properties. In order to enhance the mechanical properties of hydrogel scaffolds, we used liquid nitrogen to modify SilMA to obtain a novel N2-SilMA/gelatin-methacryloyl (GelMA) composite hydrogel. N2-SilMA was successfully detected by Fourier transform infrared (FTIR) spectroscopy and 1H nuclear magnetic resonance. Scanning electron microscope showed that the composite hydrogel still had certain arrangement characteristics of SF and dense pores which met the necessary conditions for the cell scaffold. The mechanical tests showed that the mechanical properties of SilMA were greatly enhanced after modification at ultra-low temperature. We evaluated its cytocompatibility and biocompatibility, and the results showed that the composite scaffold promoted the growth of cells. Different types of composite hydrogels were injected into ICR mice and the results showed a stable scaffold structure in vivo, suggesting their ability to promote angiogenesis. In conclusion, the N2-SilMA/GelMA composite hydrogel had better mechanical properties, excellent cytocompatibility, and biological properties compared to the other groups.