| Artificial bone scaffold material is an important content in the field of bone tissue engineering research and has great application prospects in bone defect repair.The ideal bone tissue engineering scaffold material not only need to have excellent mechanical properties,but also requires the material to have a three-dimensional porous structure interpenetrating.The contradiction between the porous structure necessary for the scaffold material and the mechanical properties of the material has been a difficult problem that is difficult to break in the field of bone tissue engineering materials.In this paper,honeycomb type polylactic acid(PLA)porous materials and chitosan/hydroxyapatite(CS/HA)porous materials were constructed by RP technology,and then the materials were modified to obtain a bone tissue engineering scaffold material with excellent mechanical properties and biocompatibility.In this paper,the RP technology,CS/HA powder filling,cold isostatic pressing,wax dissolving combined with the indirect forming method of pore forming is used to obtain the honeycomb type CS/HA porous artificial bone scaffold material with excellent mechanical properties after.Based on this,the CS/HA porous scaffold was coated with gelatin(Gel)to obtain the coated scaffold material CS/HA-Gel,and then the coated scaffold was cross-linked with glutaraldehyde(Gul)to obtain the cross-linked scaffold material CS/HA-Gel/Gul.The results of particle size analysis indicated that the raw material of the prepared material was mainly in the irregular short rod-shaped carbonized CS/HA composite with a size of 1.09-27.2 ?m.XRD results show that the introduction of CS,Gel and Gul in the porous scaffold material weakens the characteristic peak of HA.The SEM results show that the porous scaffold material has a honeycomb-like hexagonal porous structure.The CS/HA scaffold material has a rough surface,while the CS/HA-Gel scaffold material has a smooth surface.The gelatin film coated on the surface of the material covers the original CS/HA coarse particles.A small amount of dissolution occurred and the CS/HA particles were partially exposed after cross-linking modification.The results of mechanical properties test showed that both coating and cross-linking can significantly improve the mechanical strength of the scaffold material.The compressive strength of the CS/HA-Gel scaffold single coating and the third coating was 5.45 and 6.03 times of the CS/HA scaffold,respectively.The mechanical properties of the coated scaffold material are further improved after cross-linking with glutaraldehyde.After the cross-linking of the gelatin single-coating scaffold and multiple-coated scaffolds,the compressive strength of the uncrosslinked scaffolds increased by 9.72%? 73.30%,respectively.The results of in vitro degradation experiments showed that cross-linking reduced the degradation rate of the material,and the degradation rate of CS/HA-Gel/Gul was the slowest among the three scaffold materials.The results of MTT assay showed that the three honeycomb structure porous scaffold materials the standard of the cytotoxicity;the results of cell culture experiments showed that all three scaffold materials have good cell compatibility.The CS/HA-Gel and CS/HA-Gel/Gul porous scaffolds is more conducive to the early adhesion of cells,and the local cell density on the surface of the three materials did not show significant difference after 3 weeks of culture.Based on the computer-aided design of honeycomb-type porous structure data model,a PLA porous scaffold similar to CS/HA structure was directly prepared by 3D printer,and the surface modification was carried out by coating and mineralization.The SEM results show that the PLA porous scaffold material has a honeycomb-like hexagonal porous structure.The surface of the scaffold material is laminated with fibers,and there is a small gap between the fibers.The surface of the scaffold material becomes smooth after being treated with chitosan(CS)coating.After mineralization,the surface of the scaffold coating film becomes rough,and a large amount of mineral particles are deposited on the surface of the CS membrane layer.The result of the electronic universal testing machine shows that both the coating can improve the compressive strength,and the compressive strength after mineralization is slightly lower than that of the coating.The results of in vitro degradation experiments showed that the degradation rate of pure undestroy PLA scaffolds was too slow,and there was no obvious weight loss in the first 6 weeks.Coating and mineralization can accelerate the degradation of PLA scaffold,and modified scaffold are more suitable as implantable degradable artificial bone materials.The results of MTT showed that the three kinds of PLA porous scaffold materials met the standard of cytotoxicity;the fluorescence scan of cell adhesion growth showed that the cell density was larger on the modified scaffold material after 7 days,and the cell distribution was wider to the inside of the pore.It is very difficult to overcome the mechanical strength difference of bone tissue engineering porous scaffold materials,which is very important for the clinical application of artificial bone materials.According to the advantages of ligh t weight,high porosity and good mechanical properties of the honeycomb,the honeycomb-like porous scaffold material and its modified scaffold material constructed by bionics have both biologically demanded three-dimensional porous structure and excellent mechanics strength.As far as the research show that they have a good application prospects in the field of bone tissue engineering. |
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