Construction And Performance Study Of N-HA/SF/PLA/n-MgO Composite Scaffold With 3D Printing

Objective:In this study,we applied 3D printing technology to construct a bionic,osteogenic three-dimensional composite scaffold containing nano-hydroxyapatite(n-HA)silk protein(SF)composite microcrystals,nano-magnesium oxide(n-MgO)and polylactic acid(PLA),and characterised the composite scaffold to investigate its mechanical properties,biocompatibility,in vivo osteogenic ability,and to verify the bone The study was carried out to verify the bone repair capacity of the bionic,osteogenic 3D composite scaffold.This will provide more options for the treatment of bone defects.1.Using 3D printing,create n-HA/SF composite scaffold and nHA/SF/PLA/n-MgO composite microcrystals.By employing silk fiber as the starting material,replicating the creation of human bone tissue,and driving the directional growth of hydroxyapatite crystals using silk protein,a hydroxy apatite/silk protein composite particle resembling bone nanostructure was created artificially.Additionally,X-ray diffraction and transmission electron microscopy(TEM)analysis of the composite particles were performed.Using 3D printing technology,the n-HA/SF/PLA/n-MgO composite scaffold was created by preparing the bioink in accordance with the ratio of nHA/SF composite microcrystals:PLA=1:4,1 weight percent magnesium oxide(nMgO)was added,and the composite scaffold was then characterized and its mechanical properties were measured.2.Evaluation of the 3D printed n-HA/SF/PLA/n-MgO composite scaffold in vitroThe toxic effects of n-HA/SF/PLA/n-MgO composite scaffold on bone marrow mesenchymal stem cells(MSCs)and its effect on their proliferation were examined by CCK-8 method and live-dead cell staining.3.Evaluation of the D-printed n-HA/SF/PLA/n-MgO composite scaffold’s in vivo osteogenic potentialTwenty-four 7-week-old male SD rats were selected as experimental animals,and a cylindrical SD rat cranial defect model with a diameter of 5mm and a height of approximately 0.8mm was established on each side of the skull.24 experimental animals were randomly divided into 3 groups with 16 defects in each group:the blank control group(Group A),the n-HA/SF/PLA scaffold group(Group B)and the n-HA/SF/PLA/n-MgO composite stent group(Group C).Four rats in each group were executed at weeks 6 and 12,and the osteogenic ability of the 3D composite scaffold was evaluated by observing the gross visual appearance of each defect,micro-CT photography and 3D reconstruction,heart,liver,spleen,lung and kidney toxicity testing,HE staining and Masson staining of the skull defects,and immunofluorescence staining.Results:1.Making n-HA/SF composite scaffolds from 3D printed n-HA/SF composite microcrystals and PLA/n-MgO composite scaffoldsThere are no additional inorganic crystals in the HA/SF composite microcrystals since their X-ray diffraction curves resemble HA.Its distinctive diffraction peaks at particular crystallographic planes show that HA nanoneedle crystals grow quickly along particular axes and that filamentin protein can promote directional growth of HA.The CAD system designed the composite scaffold with a line width of 300 μm and a pore size of 400 μm.The porosity of the scaffold was measured by anhydrous ethanol:(62.28± 1.07)%for the n-HA/SF/PLA scaffold(group B)and(64.52±0.96)%for the n-HA/SF/PLA/n-MgO composite scaffold(group C).The compressive strength of group B was 47.7±1.2 MPa and that of group C was 53.3±1.1 MPa as measured by a testing machine.2.Evaluation of 3D-printed n-HA/SF/PLA/n-MgO composite scaffolds from a biological perspective in vitroThe cytotoxicity of the scaffolds was tested by the CCK-8 method,and the OD values of the scaffold extracts co-cultured with cells at 24h,48h and 72h were tested by enzyme marker,and the results showed that both groups of scaffolds had no significant inhibitory effect on the proliferation of MSCs.A low number of dead cells could be observed in all three groups by live-dead cell staining,and there was no significant difference between the different groups.3.Evaluation of the D-printed n-HA/SF/PLA/n-MgO composite scaffold’s in vivo osteogenic potentialThe n-HA/SF/PLA/n-MgO composite scaffold group demonstrated better osteogenic performance,followed by the n-HA/SF/PLA scaffold group,and both of them.This was determined by observing the gross view at the cranial molds of experimental animals in each group,Micro-CT photography and 3D reconstruction,heart,liver,spleen,lung,and kidney toxicity detection,HE staining at the cranial defects,Masson staining,and The scaffold material slowly deteriorated over time,the line separating it from the defect site blurred,new bone grew into the scaffold well,new bone tissue and calcium salt-containing bone tissue gradually increased at the defect site,and new bone gradually replaced the scaffold.However,no discernible rejection reaction was seen.The toxicity test in vivo did not show any abnormalities such as cell degeneration,atrophy and necrosis.Conclusion:In this study,the 3D printing technology was used to create a bionic,osteogenic 3D composite scaffold containing nano-hydroxyapatite(n-HA),silk protein(SF)composite microcrystals,nano-magnesium oxide(n-MgO),and polylactic acid(PLA).Compared to the blank control group and n-HA/SF/PLA scaffold group with stronger biomechanical properties,biocompatibility,and other characteristics The n-HA/SF/PLA scaffold was better suited as a substitute material for bone defects because it had enhanced osteogenic potential.In conclusion,the n-HA/SF/PLA/n-MgO composite scaffold has potential therapeutic usage as a material for repairing bone defects.