Study On Preparation And Properties Of CPPF/CS Composite Integrated Articular Cartilage Scaffold

Chitosan?CS?has good biocompatibility,degradability,excellent antibacterial property and plasticity.CS has a good application prospect in the repair of articular cartilage tissue defects.However,the mechanical properties of the CS scaffold are worse than normal bone tissue and cannot support the bearing of the bone implant.A common way to improve its performance is to compound it with another material.Calcium polyphosphate fibers?CPPF?has good biocompatibility,bioactivity,osteoconductivity and degradability,and its degradat-ion products are non-toxic.CPPF are widely used in tissue engineering.In this paper,based on the normal morphology of the articular cartilage tissue,the three-layer integrated articular cartilage tissue scaffold of CPPF/CS composite was prepared by freeze-drying method.First,CPPF is added to the CS solution,and after freezing and vacuum drying,the CPPF/CS composite scaffold is obtained.The CPPF/CS composite scaffold acts as a hyaline cartilage layer and a subchondral bone layer of the cartilage scaffold.Next,a KH-550modified calcium polyphosphate?CPP?glass piece was used as the calcified cartilage layer.Then,bond the three parts together as a whole with a viscous CS solution.The various properties of the integrated articular cartilage scaffold were characterized by SEM,FT-IR,XRD,compressive modulus and porosity.Experimental results show:?1?The CS scaffold was successfully prepared by freeze-drying method,and the concentration of CS was changed,and the various properties of the CS scaffold also changed.With the increase of CS concentration,the porosity,water absorption and degradation rate of CS scaffold are decreasing,but its mechanical properties are improving.By observing the SEM image,it can be seen that the CS scaffold has a three-dimensional,mesh-like,connected porous structure;the size of the CS scaffold aperture is inversely proportional to the concentration of CS.?2?CPPF was prepared by melt drawing method using calcium dihydrogen phosphate and boron oxide as raw materials.Using CPPF as a reinforcing material can improve the mechanical properties of the CS scaffold and expand the pore size of the CS scaffold,but it will reduce the porosity of the CS scaffold and accelerate the degradation rate of the CS scaffold.In addition,with the increase of the amount of CPPF added,the water absorption and mechanical properties of the CPPF/CS composite scaffold are improved,the porosity is decreased,and the degradation rate is increased.?3?A CPP glass piece was used as the calcified cartilage layer of the cartilage scaffold.The CPP glass piece can be degraded in PBS solution,and the degradation product is hydroxyapatite,which is non-toxic.However,pure CPP glass tablets degraded faster and degraded by about 37%after 30 days.Adding an appropriate amount of boron oxide?B₂O₃?can slow the degradation rate of the CPP glass sheet.?4?The integrated cartilage scaffold is divided into three layers,and the upper and lower layers are porous structures,which transport nutrients and discharge metabolites for cell growth.The intermediate layer is a dense layer that ensures sufficient mechanical properties of the scaffold.The compression modulus of the integrated cartilage scaffold was 7.45 MPa,which was degraded by about 20%after 42 days.