3D Bioprinting of Reinforced Vessels by Dual-Cross-linked Biocompatible Hydrogels

3D bioprinting offers a powerful tool to fabricate vessel channels in tissue engineering applications, but inadequate strength of the vascular walls limited the development of this strategy and reinforced channels were highly desired for vascular constructions. Herein, we demonstrated a dual cross-linking system for 3D bioprinting of tubular structures, achieved by a combination of photo-cross-linking and enzymatic cross-linking. Photo-cross-linking of gelatin methacryloyl (GelMA) was achieved with a photoactive conjugated polymer PBF under 550 nm irradiation. Enzymatic cross-linking utilized cascade reactions catalyzed by glucose peroxidase and horseradish peroxidase that can cross-link both methacrylate and tyrosine moieties of GelMA. After removing the 3D-printed sacrificial layer (Pluronic F-127), the obtained perfusable channels showed great biocompatibility that allowed endothelial cells to adhere and proliferate. Our dual cross-linking strategy has great potential in 3D bioprinting of tubular structure for biomedical applications, especially for artificial blood vessels.