Plant xylem-inspired chitosan-gelatin scaffolds reinforced with graphene oxide with a superior mechanical strength and hydrophilicity for bone tissue engineering.

The limited mechanical strength of natural hydrogels restricts their use in bone tissue engineering, while structural design is critical for enabling nutrient and waste exchange and promoting cell proliferation. In this study, we developed a centripetal directional channel structure within a chitosan (CS)-gelatin (G) matrix using directed freeze-drying, inspired by the transverse centripetal channels of plant xylem. Graphene oxide (GO) was incorporated into the CS-G matrix to enhance the pore structure and mechanical strength. Incorporating graphene oxide (GO) into the CS-G matrix enhanced pore structure and mechanical properties. The resulting GO/CS-G scaffolds exhibited a well-defined centripetal channel structure, outperforming CS-G scaffolds with random structures. Notably, water contact absorption time on the scaffold's surface decreased from 4040 ms to 151 ms, compressive strength increased from 0.25 MPa to 0.56 MPa, and Young's modulus rose from 3.19 MPa to 17.57 MPa. The scaffolds maintained structural stability after multiple 90 % compression cycles. Additionally, it demonstrated enhanced biomineralization capacity and promoted the viability and proliferation of pre-osteoblasts (MC3T3-E1). In vivo implantation results confirmed that the GO/CS-G scaffold significantly boosted new bone formation by up to 28.31 %, attributed to the synergistic effects of its centripetal directional channel structure and robust structural stability. These results highlight the GO/CS-G scaffold's potential as a promising candidate for 3D bone tissue engineering, owing to its biomimetic design, favorable mechanical properties, and excellent biological performance.