3D Printed Strontium Doped PCL/HA Bone Tissue Engineering Scaffold And Its Performance Evaluation

The repair and regeneration of bone defects is a challenge and a challenge to be solved in material science.Most of the traditional methods for the treatment of bone defects have deficiencies and limitations.Artificial bone repair materials in bone tissue engineering have been widely studied in the field of bone repair and regeneration due to the advantages of wide source and no risk of disease transmission.The core of bone tissue engineering is the construction of high-performance scaffolds,and 3D-printed bone tissue engineering scaffolds are widely used in biomedical fields because of their precise and controllable pore structure and personalization.This thesis aims to prepare bone tissue engineering scaffolds with suitable cell and bone tissue growth by biological3D printing method,to study their physicochemical,mechanical and biological properties,and to simulate the femoral stress distribution when the scaffold is implanted into the human femoral defect area using finite element method.The main research contents and conclusions are as follows:First,the melt-extrusion 3D printing technology was used to optimize the construction of the polycaprolactone/hydroxyapatite（PCL/HA）composite scaffold with different hydroxyapatite（HA）contents.the addition of HA improved the hydrophilicity and enhanced the degradation rate of the composite scaffold,with a contact angle of 71.06°and a degradation rate of 5.94%at 20%HA addition;the mechanical properties of the PCL/HA composite scaffold increased with In vitro biological experiments showed that the PCL/HA composite scaffold had good cytocompatibility and in vitro mineralization ability.Secondly,in order to improve the biological performance of the composite scaffold,based on the PCL/10HA composite,the HA was modified with strontium（Sr）doping and combined with melt extrusion 3D printing to construct the PCL/Sr HA composite scaffold.When the Sr element content is 5%,the PCL/Sr HA composite scaffold has the best compressive performance,with compressive strength and elastic modulus of24.25MPa and 176.74MPa,respectively.Biocompatibility experiments have shown that the PCL/Sr HA composite scaffold can promote the proliferation of MC3T3E1 cells,and the Sr²⁺released from the composite scaffold can promote the formation of bone tissue in vitro.Then,load desferrioxamine（DFO）on the surface of PCL/Sr5HA scaffold to construct PCL/Sr5HA@DFO composite scaffold.Comparative study of PCL/10HA,PCL/Sr5HA,and PCL/Sr5HA@DFO The osteogenic/vascular properties of composite scaffolds induced in vitro.The expression indicates that Sr²⁺and DFO can synergistically promote osteogenesis and angiogenesis in vitro.Finally,simulate the changes in femoral stress of different femoral models and implanted bone repair scaffolds for adults while static standing,slow walking,fast walking,and up and down stairs.The results showed that compared with PCL/Sr5HA composite scaffold,PCL/Sr5HA composite scaffold can better alleviate stress concentration in the defect area and bear more loads on the femur.