Preparation And Properties Of CPP/PLLA Joint Osteochondral Tissue Engineering Scaffold With "Boundary Layer Structure"

In research on articular cartilage tissue engineering,the basic composition, morphological structure, physiological function and Physiological environment of human body joint osteochondral tissues were not in-depth discussed, and the function interface connection structure, called calcified cartilage layer, that between transparent cartilage and subchondral bone layer was ignored. Based on normal osteochondral tissue and bionic biological materials, the paper has prepared articular cartilage tissue engineering scaffold containing calcified cartilage layer which is similar to host structure.Nano-hydroxyapatite(Nano-HA) was synthesized by hydrothermal synthesis and β-tricalcium phosphate(β-TCP) was synthesized by solid sintering methods. Due to the serious reunion of the Nano-HA, the research uses surface active agent Stearic acid(SA) and silane coupling agent(KH550) respectively to modificate Nano-HA. Nano-HA modified before and after were analyzed by X-Ray Diffraction(XRD) and Fourier-transform infrared spectroscopy(FT-IR), and its microstructure was observed by SEM. The results shown that Nano-HA powder was prepared provided that n(Ca)/n(P) =1.67, 150℃, 5h, Ca HPO4·2H2O and Ca CO3, KH550 and SA are successfully attached on the surface of Nano-HA, which does not change its original microstructure, still maintain certain biological activity and also make its dispensability better.The three dimensional, connecting, microporous reticulated structure of the CPP/PLLA/HA(β-TCP) joint osteochondral tissue engineering scaffolds was successfully prepared by the method of solvent casting and particulate leaching when PLLA was chosen as the substrate, self-made polycalcium phosphate fibers(CPP) fiber was chosen as reinforcing material, Nano-HA/β-TCP was chosen as degradation liquid p H regulator, CH2Cl2 was chosen as solvent and Na Cl was chosen as the pore-formed template. The mechanical properties, physical properties and microstructure of the osteochondral tissue engineering porous scaffolds was characterized respectively by AG–IS, Liquid displacement method and SEM. The degradation of scaffolds was simulated in vitro degradation experiment with PBS and the degradation performance was analyzed. According to the experimental results, scaffold properties is best under the condition of the content of HA is 5% and the content of β-TCP is 5%.The three dimensional, connecting, microporous reticulated structure and ample mechanical properties of the CPP/PLLA/HA joint osteochondral tissue engineering bionic scaffolds with “boundary layer structure” provides appropriate nutrition transportation condition, space and place to meet cartilage cell differentiation, growth. The best preparation process of the CPP/PLLA/HA joint osteochondral tissue engineering porous scaffolds is that soaking time is 1h,temperature is 180℃, holding time is 10 min under the condition of 10 MPa. The experimental results show that with the increase of HA content the porosity and density of the CPP/PLLA/HA tissue engineering scaffold with "boundary layer structure" will decline, but the degradation liquid p H of scaffolds increases, which suggests that HA can adjust the degradation liquid p H.