| Objective:Massive loss of bone tissue caused by trauma,tumors and infections often causes great harm to patients' physical and mental health.Although bone tissue has significant regeneration characteristics,complex large-area bone defects will eventually be difficult to heal due to problems such as delayed healing and secondary infections.Autogenous bone transplantation,which is the "gold standard" for repairing bone defects,has the disadvantages of limited donor sites and increased secondary trauma,Allogeneic bone transplantation has the risks of immune rejection and pathogen transmission,which has brought great challenges to the clinical reconstruction of bone defects.Bone tissue engineering technology has also emerged at the historic moment,which has brought hope to the treatment of bone defects.Bone tissue engineering is to use a degradable bioscaffold material with appropriate mechanical properties to implant bone defect sites,as a temporary template similar to the natural extracellular matrix,to promote the adhesion,proliferation,and osteogenic differentiation of mesenchymal cells until a new bone matrix is generated.Common bone scaffold materials such as Sodium alginate(SA),Chitosan(CS),collagen,etc.have good biocompatibility,however,due to the low mechanical properties and the fast degradation rate,it cannot be matched with the formation rate of new bone tissue and cannot be widely used.Therefore,it is urgent to develop scaffold materials with good biological properties,suitable mechanical properties and controllable degradation rate.Graphene oxide(GO)has a two-dimensional single-layer carbon atomic structure,and its surface contains a large number of oxygen-containing functional groups.It has the advantages of high specific surface area and high mechanical properties,and has a broad application prospect in biological imaging,drug loading and tissue engineering,therefore,manyscholars combined GO into scaffold materials as an additive to improve the mechanical properties and degradation rate of scaffolds,and promote cell adhesion and proliferation.This experiment intends to incorporate different weight percentages of GO into SA and CS materials with good biocompatibility.The composite scaffold material is constructed by freeze-drying technology to study the effect of different amounts of GO on the physical and chemical and biological properties of the scaffold.The optimal content of GO in the composite scaffold is expected to develop a new bone scaffold material with enhanced mechanical properties and improved biological properties.Methods:1.Synthesis of GO-SA-CS composite scaffoldGO-SA-CS composite scaffolds with graphene oxide weight percentages of 0wt%,0.3 wt%,0.5 wt%,0.7 wt%,and 1 wt% were prepared by freeze-drying methods,respectively.Among them,SA-CS was the control group,and 0.3 wt%,0.5 wt%,0.7wt%,and 1 wt% GO-SA-CS was the experimental group.2.Fourier transform infrared spectroscopy was used to analyze the chemical composition of the composite scaffold;Scanning electron microscope was used to observe the internal microstructure of the scaffold and calculate the pore size;The swelling test was used to detect the swelling ratio;Liquid replacement method was used to calculate the scaffold porosity;In vitro degradation experiment was used to evaluate the degradation performance of the scaffold;The electronic universal testing machine detects the mechanical properties of the svaffold.3.CCK-8 kit was used to detect in vitro cytotoxicity of scaffold extracts from each group Scaffolds on mouse preosteoblast(MC3T3-E1).Results:1.The specific absorption peaks obtained by Fourier transform infrared spectroscopy prove that we have successfully synthesized SA-CS and GO-SA-CS composite scaffold materials.At room temperature,the composite scaffolds in each group were all sponge-like solid structures,with tiny pores visible on the surface,and the scaffolds in the control group were white,while the scaffolds in the experimentalgroup were tan with the increase of GO content.2.Observed under the scanning electron microscope,each group of the scaffold has a similar three-dimensional network structure inside.Compared with the simple SA-CS scaffold,the addition of GO will reduce the size of the scaffold and increase the thickness of the hole wall,and it is proportional to the GO content.3.Compared with the SA-CS scaffold in the experimental group,the mechanical properties of the scaffold improved as the GO content increased,and the difference between the groups was statistically significant(P<0.05);The degradation rate also decreased.The results showed that on the 21 st day of in vitro degradation,the degradation rate of the scaffold in the control group was as high as 64.41%,and the addition of GO reduced the degradation rate to below 50%,and the higher the content,the slower the degradation rate.The swelling ratio results showed that as the GO content increased,the swelling ratio of the scaffold gradually decreased,and the difference between the groups was statistically significant(P<0.05);The porosity results show that the effect of adding GO on the porosity of each group of scaffolds is not obvious,and the difference between the groups is not statistically significant(P> 0.05).4.In vitro cytotoxicity results showed that when GO content was 0.3 wt%,cell survival rate was the highest,while when GO content was 0.7 wt% and 1 wt%,cell activity was significantly inhibited,resulting in cell death.Conclusions:1.GO-SA-CS composite scaffolds with different GO contents(0 wt%,0.3 wt%,0.5 wt%,0.7 wt%,1 wt%)were successfully synthesized.2.The composite scaffold with GO showed certain advantages in swelling ratio,degradation rate and mechanical properties.The cytotoxicity results also showed that when the GO content was 0.3 wt%,the biocompatibility of the composite scaffold reached its best,and the comprehensive scaffold physical characterization results,The final optimal concentration of GO improved SA-CS scaffold was 0.3 wt%,which laid a good foundation for GO in the later experiments. |
PDF Full Text Request