Construction And Properties Research Of 3D Printed Self-lubricating Bionic Cartilage

Objective: A 3D-printed graphene/polyvinyl alcohol hydrogel scaffold was prepared,and the pore size of the scaffold was loaded with hyaluronic acid with excellent lubricating properties,so as to achieve a low-friction surface and high mechanical properties of the composite scaffold,and further evaluate the potential of composite scaffolds as biomimetic articular cartilage.Methods: We designed a biomimetic hydrogel scaffold which was similar to the articular cartilage function.Using direct-writing 3D printing technology for doublehead printing of ink,the main frame of the stent was printed with GO/PVA ink,the hollow part was filled with HA/F127 lubricant,and finally the stent was encapsulated with GO/PVA ink to form a complete self-lubricating biomimetic cartilage.1)Prepare GO/PVA bioinks with different GO concentrations（0 mg/m L,0.5mg/m L,1 mg/m L and 2 mg/m L）,and the printability of the ink was evaluated by detecting its viscosity and rheology.Through the optimizations in pressure and speed of 3D printing technology,the best printing pressure and speed were chosen,and four groups of GO/PVA hydrogel scaffolds（G0P,G0.5P,G1 P and G2P）were prepared through freezing-thawing cycles.2)The surface morphology and pores of the printing scaffolds were observed by SEM.The formation of new chemical bonds were verified by FT-IR.The water content,swelling rate,degradation characteristics and mechanical properties of each group of printed scaffolds were detected.The optimum experimental parameters were chosen from the above experimental characterizations.3)The tribological test showed that the addition of GO reduced the friction coefficient in a certain range,and the friction coefficients of G0 P,G0.5P,G1 P and G2 P groups were 0.18,0.12,0.09 and 0.11,respectively.HA/F127 can significantly improve the friction coefficient,and the friction coefficient of G1P-HA/F127 group was reduced to 0.05.4)MTT test results showed that the cell survival rate gradually decreased with the increase of GO,The cell viability of G0 P,G0.5P,and G1 P groups were more than80 %.The results of Calcein AM/PI staining also proved the biosafety of the material.Conclusion: The 3D printed GO/PVA hydrogel scaffold group has a uniform porous microstructure and suitable degradability.The G1P-HA/F127 hydrogel has more excellent mechanical strength similar to natural cartilage,lower friction coefficient and better biocompatibility.Based on the tribological test and wear scratch observation of each group of scaffolds,it was shown that the GO/PVA hydrogel scaffold loaded with HA/F127 had self-lubricating and friction-resistant capabilities,confirming that the hydrogel scaffold had the potential of biomimetic articular cartilage.