Study On 3D Printed Biomimetic Apatite Composite Scaffolds For Repairing Rabbit Cranial Defect

Apatite is dominant solid mineral phase within the skeletal tissues of human with excellent bioactivity,biocompatibility,osteoconductivity and osteoinductivity.Biomimetic apatite composites are prepared by mimicking in vivo biomineralization and have been widely used in bone tissue engineering for their excellent properties.In order to mimic the structure and property of natural bone and research the influence of Sr,biomimetic self-assembly of HAP and Sr-containing HAP?Sr-HAP?were synthesized by using type-I collagen as fibrous templates and citrate as soluble templates in this study.FTIR,XRD,SEM,TEM and TG were used to analyze the physical and chemical properties of the HAP and Sr-HAP nanoparticles.The results showed that Sr-HAP nanoparticles synthesized with Sr:?Sr+Ca?=5 mol%showed Sr:?Sr+Ca?=5.8 mol%measured by EDX.Both HAP and Sr-HAP nanoparticles were sheet structure with 40-50 nm×15 nm.And the quality of inorganic phase takes up about 87 wt%of the HAP or Sr-HAP powders.Three-dimensional printing?3D printing?technology has been developed rapidly these years.It is easy to fabricate scaffolds with controlled shape,size,pore size and porosity by 3D printing technology and all these parameters are important for bone tissue engineering scaffolds.In this study,we used biomimetic self-assembly of HAP/Sr-HAP,gelatin and sodium hyaluronate to print porous scaffolds at low temperatures.In vitro and in vivo experiments were carry out by using MC3T3-E1 cells and New Zealand rabbits critical-sized calvarial defects.Results showed that MC3T3-E1 cells attached well to the HAP and Sr-HAP scaffolds.The Sr ions could enhance cell proliferation and differentiation.Furthermore,three-dimensional printed HAP/Sr-HAP scaffolds could promote bone reparation and Sr-HAP scaffold could significantly promote bone repairing than the HAP scaffolds.Surface treatment is a major method to enhance the properties of scaffolds.In this study,10×simulated body fluid?10×SBF?was used to deposit minerals onto the 3D printed HAP scaffolds.XRD and SEM were used to analyze the physical and chemical properties of the treated scaffolds.In vitro experiments were carry out by using MC3T3-E1 cells to analyze the biological properties of the scaffolds.The results showed that product of mineralization is CaHPO₄ phase.The treated scaffolds showed higher biological properties than the un-treated scaffolds.The method will be optimized to improve biocompatibility and property to promote bone repairing of the scaffolds in the future.