The Architecture Design And Fabrication Technology Of Biodegradable Scaffolds

Bone tissue engineering is one of the most important method in bone defect repair,the key of which is the porous scaffold owning specific three-dimensional structure and fine biological compatibility.When the porous scaffold is implanted into body,the scaffold can gradually degrade and be completely replaced by new bone finally.Rapid prototyping can achieve more precise control of framework and explore the relationship between scaffold structure and performance,helping seek the optimal design parameters considering conflicts in requirements,such as the porosity of scaffold and mechanical properties.This research focus on seeking the correlation in the architecture and porosity of scaffold with degradation property,fabricating the porous scaffold by 3D bioplotter.First,the macrostructure and microstructure of the porous scaffold are established.The form of porous scaffold is established by three-dimensional reconstruction of femur which converts CT images to stereochemical structure by Mimics and Geomagic Studio.With size optimization of finite element software,the unit with spherical pore is established.The gyroid model is one of triply periodic minimal surface models,which is established by K3 Dsurf and Rhinoceros.The topological structure is established by topology optimization of unit with circular holes.Finally the porous scaffold with the femur contour is obtained by boolean operation.According to the degradation mechanism of PLA,the degradation model is established based on bulk degradation.The constitutive relationship of the material is redefine by the user subroutine UMAT in ABAQUS analysis software.The properties of material change as time when the porous scaffold degrades.Comparing three kind of unit in different porosity,mechanical properties are analyzed by simulation on biological material degradation.The simulation shows that the unit which is established by topology optimization owns better mechanical properties than others at first,but the unit which is established by gyroid owns better mechanical properties than the unit which is established by topology optimization when they degrade for a long time and the difference is more obvious when the porosity is increased.Comparing the advantages of different biomedical materials,PLA,?-TCP and HA are chosen to manufacture composite material and 1,4-dioxane is chosen to be the solvent.The pressure of nozzle is controlled by viscosity of slurry.The porous scaffolds with different porosity and architecture are fabricated by 3D bioplotter.The porous scaffolds are put into simulated body fluid.The quality change of the porous scaffold is measured in vitro degradation experiment.The surface morphology of the porous scaffold is characterized by scanning electron microscope.The mechanical properties is tested by uniaxial compression test.