Preparation And Properties Of Functionalized Multi-walled Carbon Nanotubes/Chitosan-Zinc Composite Scaffolds

Objective:Functionalized multi-walled carbon nanotubes/chitosan-Zn?f-MWCNT/CS-Zn?composite scaffolds were prepared and their properties were tested.The potential of application as tissue engineering bone was discussed.Methods:First part:Preparation,characterization and cytotoxicity of functionalized multi-walled carbon nanotubes/chitosan composite scaffolds?f-MWCNT/CS?.CS and f-MWCNT were used as the main raw materials,and three f-MWCNT/CS composite scaffolds with different f-MWCNT concentration were prepared by "solution blending" in combination with "freeze-drying" method,the concentrations of carbon nanotubes in the composite scaffolds were 0.1%,0.5%,1%,respectively.The morphology of the composite scaffolds was observed by scanning electron microscopy?SEM?.Mouse osteoblasts?MC3T3-El?was used to evaluate the cytotoxicity of the scaffolds by MTT method.According to the above test results determine the optimum content ratio of f-MWCNT and CS in the composite scaffold for the follow-up experiment.The second part:Preparation,characterization and biological properties of the functionalized multi-walled carbon nanotubes/chitosan loaded zinc?f-MWCNT/CS-Zn?composite scaffolds.The f-MWCNT/CS-Zn composite scaffolds were prepared by adding the different concentrations of ZnSO₄·7H₂O to the mixed solution of carbon nanotubes and chitosan?the concentrations of Zn in the composite scaffolds were 0.2%,1%,2%,respectively?by "solution blending" in combined with the "freeze-drying" method.The morphology of the composite scaffold was observed by scanning electron microscopy,the surface hardness was measured by nanoindenture,the tensile strength was measured by the electronic universal testing machine,and the phase analysis was carried out by wide angle X-ray diffractometer.Fourier Transform infrared spectroscopy?FTIR?was used to analyze the interaction between the molecules of the composite scaffolds.The antibacterial activity of the composite scaffold was evaluated by antibacterial testing.The osteoblast proliferation ability of f-MWCNT/CS-Zn composite scaffolds was evaluated by MTT assay using mouse osteoblasts?MC3T3-El?.Results:First part:The three groups of f-MWCNT/CS composite scaffolds prepared in the first part of the experiment have three-dimensional microporous structure with high porosity and pore size between 50-300?m,which is suitable for osteoblast adhesion and growth.The surface hardness of f-MWCNT/CS scaffolds was significantly higher than that of pure CS scaffolds,and the surface hardness of f-MWCNT/CS scaffolds increased with the increase of f-MWCNT content in the composite scaffolds,the differences were statistically significant?P<0.01?.Tensile strength test showed that the tensile strength of the f-MWCNT/CS scaffolds was significantly higher than that of the pure CS scaffolds,and the tensile strength and elastic modulus of the f-MWCNT/CS scaffolds were increased with the increase of f-MWCNT content in the scaffolds,and the difference was statistically significant?P<0.01?.XRD showed that the addition of 0.1%,0.5% and 1% f-MWCNT had no significant effect on the crystal structure of CS of the composite scaffolds.Cytotoxicity assay showed that 0.1%f-MWCNT/CS scaffold and 0.5%f-MWCNT/CS scaffolds were rated grade 0-1 and had good biocompatibility.1% f-MWCNT/CS scaffolds were rated grade 2,and has mild cytotoxicity on osteoblasts.The second part:The structure of f-MWCNT/CS-Zn composite scaffolds prepared in the second part of the experiment were similar to those of the f-MWCNT/CS scaffolds prepared in the first part of the experiment.The surface hardness test showed that adding 0.2%,0.1% and 2% Zn in composite scaffolds had no significant effect on the surface hardness of f-MWCNT/CS-Zn scaffolds.The surface hardness of f-MWCNT/CS-Zn scaffolds and f-MWCNT/CS scaffolds was similar,the difference was not statistically significant?P>0.05?.Tensile strength test showed that addition of 0.2%,0.1% and 2% Zn had no significant effect on the tensile strength and elastic modulus of f-MWCNT/CS-Zn scaffolds compared with f-MWCNT/CS scaffolds.The mechanical properties of three groups of f-MWCNT/CS-Zn scaffolds and MWCNT/CS were similar,the difference was not statistically significant?P>0.05?.XRD showed that addition of 0.2%,1%,2% Zn had no significant effect on the crystal structure of CS.The FTIR results showed that the functional groups of f-MWCNT and the charged groups of CS had intermolecular interactions with Zn2+.The anti-bacterial experiments showed that the f-MWCNT/CS-Zn composite scaffolds had better antibacterial activity against Staphylococcus aureus and Escherichia coli than that of f-MWCNT/CS scaffolds.With the increase of Zn content in the scaffolds,the antibacterial effect of the composite scaffolds was enhanced,and the difference was statistically significant?P<0.01?.The results showed that f-MWCNT/CS-0.2%Zn scaffolds and f-MWCNT/CS-1%Zn scaffolds had better proliferative effect on osteoblasts than f-MWCNT/CS scaffolds,the difference was statistically significant?P<0.05?.The proliferation of osteoblasts of f-MWCNT/CS-2%Zn scaffolds was less than that of f-MWCNT/CS scaffolds,the difference was statistically significant?P<0.05?.Conclusion:The f-MWCNTCS-1%Zn composite scaffolds prepared in this study have stable chemical binding.The addition of 0.5% f-MWCNT and 1% Zn has no obvious effect on the CS crystal structure of the scaffolds.F-MWCNT/CS-1%Zn composite scaffolds have good microstructure,better mechanical properties,excellent antibacterial activity and promoting osteoblast proliferation performance,and have potential applications in bone tissue engineering.