3D Pringting Process And Performance Reseach Of HA/PCL Bone Tissue Engeneering Scaffold

Damage to bone is one of the common diseases in daily life.The way to treat the disease so far is generally bone grafting technology.For patients with severe bone loss,titanium alloy transplantation is needed.Both methods have the respective disadvantages.As an emerging field,tissue engineering has made up for the current shortcomings to some extent.Tissue engineering stent graft technology has broad prospects in the treatment of bone defects.This topic uses polycaprolactone(PCL)with good biocompatibility and hydroxyapatite(HA)with good bone conductivity as raw materials.The PCL 3D printing and HA/PCL 3D printing process were completed by self-developed screw extrusion 3D printer.The tissue engineering scaffold with certain porosity and mechanical properties was successfully prepared,which is expected to be applied in bone tissue engineering.Based on the basic principles of fused deposition modeling(FDM),this paper develops a three-dimensional printing and forming device that utilizes screw melt plasticization and precise metering and extrusion with a melt pump.The molding process of the device was studied,and the 3D printing study of tissue engineering scaffolds was carried out using the device.The experiments done and the conclusions reached are as belows:(1)Using this equipment to print PCL pellet raw materials,the influence of printing temperature and printing layer height on printing precision was studied.The printing precision of PCL products was improved through experimental research.The mechanical properties of the products prepared by the process and the injection molding process were studied.Comparing the experimental data,the tensile strength and bending strength of the PCL products prepared by the process were higher than those of the injection molding,respectively.(2)Nano-HA/PCL and micro-HA/PCL composite particles with HA mass fraction of 20%were prepared by twin-screw extruder and pelletizer,and 3D printing experiments were carried out to prepare two composite tissue engineering scaffolds.The porosity and mechanical strength of nano-HA/PCL tissue engineering scaffolds were higher than those of micro-HA/PCL tissue engineering scaffolds.The distribution of HA particles was observed by electron microscopy.The results showed that nono-HA was evenly distributed in the composite,and micro-HA occurred agglomeration,therefore,nano-HA/PCL composite FDM 3D printing has more potential applications in bone tissue engineering.(3)HA/PCL composites with different contents of hydroxyapatite were prepared by melt blending with nano-hydroxyapatite(nano-HA)and polycaprolactone(PCL)as raw materials.The properties of the printed products were characterized by mechanical analysis,differential scanning calorimetry,thermogravimetric analysis and X-ray diffraction analysis.The results show that with the increase of HA mass fraction,the tensile strength and bending strength of HA/PCL composite 3D printed products first increase and then decrease,the compressive strength increases,the crystallization performance becomes better,and the thermal stability decreases.When the HA mass fraction is 20%,the tensile strength and bending strength of the 3D printed specimens are the largest,respectively 23.3 MPa and 21.4 MPa,and the nano-HA/PCL composite with a HA mass fraction of 40%has the highest compressive strength of 31.4 MPa.The HA/PCL composite printed product contains only two phases of HA and PCL,which is beneficial to its good biological activity and is expected to be applied in biological tissue scaffolds.