| With the aging of the population and various external factors,the number of patients with bone disease and bone defect has increased year by year so that the demand for bone defect repair is increasing.The most commonly used autologous bone grafts in the clinic have problems such as limited donors and secondary injury to patients.However,allogeneic bone grafts have problems such as immune rejection.Therefore,the research of new bone repair has important value and significance.In recent years,the development of tissue engineering in the medical field and the research of advanced rapid prototyping technology have provided new directions for better construction of bone defect repair scaffolds.In this paper,a porous biphasic calcium phosphate(BCP)scaffold prepared by 3D printing technology was studied,and the collagen coating modification method of BCP scaffold was further explored,so as to achieve better simulation of natural bone.In this paper,the composition and structure of bone and the substitute materials of common bone defect prosthesis were introduced firstly.The common materials and preparation methods of bone tissue engineering scaffold were summarized,which laid a theoretical foundation for 3D printed bone tissue scaffold.Secondly,BCP(composed of hydroxyapatite(HAP)and ?-tricalcium phosphate(?-TCP))and type I collagen are selected as the main materials for bone tissue scaffolds.Through printing,the bio-slurry which can be stably printed and the printing parameters with good molding effect are obtained: the optimum solid phase content of the biological slurry was 36 vol%,the conical needle with a diameter of 0.41 mm,the printing speed of 7-10 mm/ s,air pressure 0.28-0.35 MPa.Through the thermogravimetric analysis,the phase analysis and the mechanical properties test of different sintering temperatures of the manufactured BCP scaffold,it is concluded that 1150 °C was the best sintering temperature,which can ensure the purity of the scaffold material and the mechanical properties of the scaffold.BCP scaffolds were coated with different concentrations of collagen,and the physical properties such as mechanical properties,micromorphology,porosity and water absorption of BCP and collagen/BCP scaffolds were tested.The results showed that the compressive strength and porosity of the scaffold were not affected,meanwhile,0.5 mg/m L collagen coating not only increased the elasticity of the scaffolds,but also significantly enhanced the water absorption of the scaffolds.The BCP scaffold fabricated in this study had a multi-stage pore structure with the macropore diameter of 285.75 ± 5.63 ?m and the micropore diameter about 1 ?m,the porosity of 64%,the compressive strength of 5.65 ± 0.22 MPa,and the compressive modulus of 109.46 ± 7 MPa;the compressive strength of the collagen/BCP scaffold was 4.99 ± 0.15 MPa and the compressive modulus was 95.24 ± 0.57 MPa,which met the requirements of natural cancellous bone.The biocompatibility of the scaffold was evaluated by in vitro co-culture of bone marrow mesenchymal stem cells(BMSCs)and three-dimensional scaffolds and cell proliferation,cell viability,cell adhesion and osteogenic gene expression experiments.The results showed that the fabricated BCP and collagen/BCP scaffolds had good biocompatibility,while cell adhesion,migration,proliferation and gene expression of collagen/BCP scaffolds were significantly better than those of pure BCP scaffolds,indicating that the collagen/BCP scaffolds were more similar to natural bones and showed better biocompatibility and osteoinductivity.In summary,the collagen/BCP scaffold prepared by 3D printing technology not only has high porosity and interconnected pore structure,but also has mechanical properties that satisfy the requirements of cancellous bone,as well as good biocompatibility and osteoinductivity.Therefore,it has important research value and broad application prospects. |
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