| Due to poor cartilage healing ability and limited self-healing ability of osteochondral defects,there is no clinically effective drug to promote the healing of osteochondral defects.Therefore,osteochondral repair requires surgery,and tissue engineering scaffolds are considered promising in osteochondral regeneration surgery.s material.Since osteochondral defects usually involve damage to cartilage and subchondral bone below,tissue scaffolds must have discrete or continuous gradients in terms of cell composition,growth factors,material composition,structure,mechanical properties,and stability.In order to meet the requirements of osteochondral repair scaffolds,this subject has successfully prepared CS biological scaffolds,CS/BG biological composite scaffolds and CS-CS/BG biological gradient scaffolds using cryo-3D printing pneumatic extrusion technology.The optimal printing parameters of the scaffold were explored,the macroscopic and microscopic morphology of the scaffold were characterized through material science and biological tests,the water absorption and porosity of the scaffold were measured,and the mechanical properties and biological properties of the scaffold were studied.The CS biological scaffolds,CS/BG biological composite scaffolds and CSCS/BG biological gradient scaffolds prepared in this project all have regular interconnected gap structures with pore sizes between 300 and 500 nm.At the same time,there are small holes with irregular shapes on the wire of the scaffolds(pore sizes range from a few nm to dozens of nm).It is beneficial to the growth of cells and tissues and the transport of nutrients.BG granules made the surface of the scaffold more rough and conducive to cell adhesion.All scaffolds have good hydrophilicity,high water absorption(up to 1482.31%)and high porosity(up to 96.29%).The higher the proportion of BG in biological scaffolds,the worse the hydrophilicity and the lower the water absorption and porosity.However,all biological scaffolds can meet the requirements of water absorption and porosity of tissue engineering scaffolds.All scaffolds had good tensile strength(up to 0.76MPa),promoted the proliferation of BMSCs,and had good biocompatibility.During the degradation process,BG can release bioactive factors,which can promote the proliferation of BMSCs.Among the CS biological scaffolds,CS/BG biological composite scaffolds and CS-CS/BG biological gradient scaffolds prepared in this subject,the CS-CS/BG biological gradient scaffold has the unique advantages of biological gradient and can simulate natural osteochondral structure.The field of osteochondral repair has great potential and application prospects. |
