3D Printing Composite Silicone Rubber-Calcium Phosphate Silicate Bioceramics Bone Scaffold For The Treatment Of Bone Defects

As a common clinical disease,bone defects seriously affect the life quality of patients.Although bone tissues have sufficient regenerative capacity,large size and complex geometric defects can limit the regeneration process,so a suitable graft is needed to promote bone defects recovery.Calcium phosphate silicate bioceramics have good mechanical properties and biological activity,and have broad application prospects.Silicone rubber has excellent physiological inertia and chemical stability,and is widely used in the medical field.In this study,calcium phosphate silicate bioceramics were compounded with silicone rubber.The bone scaffolds were prepared by 3D printing technology at room temperature,and a series of physical and chemical properties tests and molecular experiments proved that the bone scaffolds have good physical and chemical properties and biocompatibility.Four sets of bioceramics pastes with different silicone rubber contents were prepared,and the final setting time,compressive strength and porosity were tested.The ratio of silicone rubber content was 15%to prepare bone scaffolds with pore sizes of 0.7 mm and 0.6 mm.The microstructure of the bone scaffolds were observed by scanning electron microscopy.The crystal phase of the composite was analyzed by X-ray diffraction.The spectral signal of the powders were analyzed by Raman spectroscopy.The bone scaffolds were immersed in SBF solution and Tris-HCl solution for simulated mineralization experiments and in vitro degradation experiments.The extract culture medium was prepared and co-cultured with osteoblasts for 24 h and 72 h to test the cell proliferation efficiency.PCR Array was used to screen for genes that were significant up-regulated in the TGF-β pathway and the BMP pathway.The detailed process of promoting osteoblasts proliferation in the pathway was explored by RT-PCR experiments.The experimental results show that the final setting time and porosity of the bioceramics pastes increase significantly with the increase of the silicone rubber content,while the compressive strength decreases with the increase of the silicone rubber content.The bone scaffolds have regular external structure and controllable microscopic pore structure with good mineralization and biodegradability.XRD and Raman detection proved that the hydration of CPSC occurred,and the silicone rubber affected the physical and chemical properties by affecting the hydration process of the CPSC.The composite bioceramics bone scaffolds can promote the proliferation of osteoblasts and have good biocompatibility and biological activity.The amplification efficiency of the Nodal gene showed a significant increase while the rest of the gene changes were not significant.By calculating the amplification efficiency of key genes in the two pathways and analyzing the pathway maps,the bone scaffolds promote osteoblasts proliferation mainly by affecting the BMP pathway.