3D printing of chitooligosaccharide-polyethylene glycol diacrylate hydrogel inks for bone tissue regeneration.

To date, lack of functional hydrogel inks has limited 3D printing applications in tissue engineering. This study developed a series of photocurable hydrogel inks based on chitooligosaccharide (COS)-polyethylene glycol diacrylate (PEGDA) for extrusion-based 3D printing of bone tissue scaffolds. The scaffolds were prepared by aza-Michael addition of COS and PEGDA followed by photopolymerisation of unreacted PEGDA. The hydrogel inks showed sufficient shear thinning properties required for extrusion 3D printing. The printed scaffolds exhibited excellent shape fidelity and fine microstructure with a resolution of 250 μm. By increasing the COS content, the swelling ratio of the scaffolds decreased, while the compressive strength increased. 3D printed COS-PEGDA scaffolds showed high viability of human bone mesenchymal stem cells in vitro. In addition, scaffolds containing 2 wt% COS showed significantly higher alkaline phosphatase activity, calcium deposition, and bioactivity in simulated body fluid compared to the control (PEGDA). Altogether, 3D printed COS-PEGDA scaffolds represent promising candidates for bone tissue regeneration.