A Novel Silk Fibroin/Nano-Hydroxyapatite Caffolds Composites For Bone Regeneration

Oral and maxillofacial diseases can cause jaw bone defects,which have a great impact on patients' quality of life.At present,there are limited repair methods for clinical repair,the emergence of tissue engineering provides new ideas and methods.Silk Fibroin SF has been widely used clinically as an FDA-approved biosafety material.nano-hydroxyapatite n HA is the main component of hard bone tissue and can be used to repair local Bone defect,but its poor plasticity and high brittleness can not be used as a repair material for medium and large bone defects.In this study,we first used porous silk fibroin scaffolds as the main body and prepared different silk fibroin / nanohydroxyapatite composite scaffolds by using salt / formic acid dissolution technology.We systematically evaluated the characterization and mechanical properties of the scaffold materials.Assay,secondly study the promotion effect of composite scaffold material on the adhesion,proliferation and osteogenic differentiation of bone mesenchymal stem cells(BMSCs).Finally,by constructing a5 mm bone defect model of rat skull,study the composite scaffold material in animals.In vivo repair of bone defects provides new ideas for tissue engineering repair of oral and maxillofacial bone defects Objectives1.Develop a new method for preparing SF-n HA composite materials,and evaluate the characterization and mechanical properties of the prepared SF porous scaffolds and SF-n HA composite scaffolds.2.Determine whether the composite materials of each group can promote the adhesion,proliferation,and osteogenic differentiation of BMSCs through local effects,and evaluate their biological safety and osteogenic induction.3.In vivo animal experiments were performed to evaluate the biocompatibility of each group of materials and the ability to guide bone regeneration and reconstruction,and to find the most suitable composite material for bone defect repair.Methods1.Rapid preparation of SF-n HA composite scaffolds with different contents by a novel salt / formic acid dissolution method,scanning electron microscopy and laser confocal microscopy microscopy observation and characterization,Fourier spectroscopy acquisition of infrared spectrum analysis of material composition,and X-ray diffraction for characterization analysis,And universal testing machine for compression experiments.2.Co-cultivate rat bone marrow mesenchymal stem cells and composite scaffold materials,observe the cell proliferation and adhesion with scanning electron microscope,and then co-culture the cells for DNA content,alkaline phosphatase content,calcium content,Runx2,OCN,type I The content of collagen was measured,and the in vitro biological safety and osteogenic ability of the materials were evaluated from the perspective of in vitro cell experiments.3.A 5mm full-thickness bone defect model of the rat skull was prepared,and the scaffold materials of each group were implanted into the bone defect model.The in vivo osteogenic properties of the material were analyzed and analyzed by Micro-CT,HE staining,immunohistochemical and other detection methods.Results:1.Nano-hydroxyapatite can be evenly distributed in the composite scaffold material prepared by the new salt / formic acid dissolution method.Both Fourier spectroscopy and XRD suggest that the materials are physically combined.Compression experiments prove that the materials have a certain ability to resist compression.2.Co-cultured BMSCs showed good adhesion ability.DNA content,ALP,calcium content,Rux2 and OCN gene detection results showed that BMSCs could proliferate well and differentiate into bone.The difference between SF-20 HA and other groups was statistically significant(*P<0.05).3.Composite scaffold materials can promote the repair of skull defects in rats,and the s F-20 HA group showed statistically significant differences from other groups in terms of micro-CT,bone volume fraction,bone density and immunohistochemical indexes(*P<0.05).ConclusionIn this study,a novel salt / formic acid dissolution method was used to prepare a uniformly dispersed silk fibroin / nanohydroxyapatite composite scaffold material with good mechanical properties in a short time,and then the material was biocompatible and formed in vitro and in vivo.Bone characteristics were studied, and it was found that SF-n HA with a mass fraction of 20% has certain advantages in osteogenesis,providing a new direction for the study of oral and maxillofacial bone tissue engineering scaffold materials.