Preparation And In Vitro Study Of Nano-silver-PDLLA Antibacterial Absorbable Scaffold

Objective: Nano-silver PDLLA absorbable scaffold was prepared by 3D printing technology combined with ultrasonic spraying technology,which added antibacterial properties to alveolar bone incremental material.The characterization,physical properties,cell proliferation activity and antibacterial effect of nano-silver PDLLA scaffolds were explored through scaffold characterization,mechanical property analysis,in vitro cell experiments and antibacterial experiments,which provided preliminary research basis for animal experiments and clinical applications.Methods:(1)PDLLA absorbable scaffold was made of PDLLA powder by 3D printing technology,and then nano silver was evenly sprayed on the scaffold by ultrasonic spraying technology.(2)The characterization and physical properties of pure PDLLA absorbent scaffolds and nano-silver PDLLA absorbent scaffolds with different concentrations were observed by scanning electron microscopy(SEM),X-ray energy dispersive spectroscopy(EDS),porosity measurement and mechanical property analysis.(3)Blank group(containing only culture medium),control group(containing only culture medium and P3 generation rat bone marrow mesenchymal stem cells),pure PDLLA absorbable scaffold group and different concentrations of nano silver-PDLLA absorbable scaffold group were set up.CCK-8 was used to analyze the effects of nano silver-PDDLA scaffold on cell proliferation activity and cytotoxicity.(4)Blank group,pure PDLLA absorbable scaffold group and different concentrations of nano silver-PDLLA absorbable scaffold group were set up,and the bacteriostatic zone method(ZOI method)was used to observe the bacteriostatic status of scaffolds.Results:(1)Nano silver was uniformly sprayed on the 3D printed PDLLA absorbent scaffolds by spraying technology.The scaffolds had uniform texture at room temperature,and all the printed parts had similar macro structure.(2)Similar structures were observed among the scaffolders in each group under scanning electron microscopy.The distribution of silver nanoparticles on the scaffolders was clearly observed in the silver-Pd Lla group,and the uniform distribution of silver nanoparticles on the scaffolders was also confirmed by X-ray energy dispersive spectroscopy(EDS).The results of porosity measurement showed that there was no significant difference between the PDLLA scaffold containing nano silver and the pure PDLLA scaffold(P > 0.05).There was no significant difference in the yield strength and elastic modulus between pure PDLLA scaffold and nano-silver PDLLA scaffold(P > 0.05).(3)Pure PDLLA scaffold and low concentration(20ppm,50ppm)nano-silver PDLLA scaffold did not affect cell proliferation and had no toxicity to cells,and there was no statistical difference between the control group(containing only medium and P3 generation rat bone marrow mesenchymal stem cells)(P > 0.05).High concentration(100ppm)of nano-silver PDLLA scaffold affected cell proliferation,which was statistically different from control group(containing only medium and P3 generation rat bone marrow mesenchymal stem cells)(P < 0.05).(4)The results of ZOI showed that nano-silver PDLLA absorbable scaffold had antibacterial effect on Escherichia coli,and the antibacterial effect increased with the increase of nano-silver concentration,and the antibacterial effect of 100 ppm concentration was the strongest.Conclusion:(1)In this experiment,PDLLA absorbable scaffold was prepared by 3D printing technology,and silver nanoparticles were sprayed on the scaffold by ultrasonic spraying method.Scanning electron microscopy and energy spectrum analysis confirmed that silver ions were evenly distributed on the scaffold,and the nano-silver-PDLLA antibacterial absorbable scaffold had good porosity,compressive strength and elastic modulus.It was confirmed that the addition of silver nanoparticles did not change the porosity,compressive strength and elastic modulus of pure PDLLA scaffolds.(2)Cell proliferation experiments confirmed that low concentration(20ppm,50ppm)of nano-silver-PDLLA antibacterial absorbable scaffolds had good biocompatibility and no toxicity to cells,while high concentration(100ppm)of nano-silver-PDLLA antibacterial absorbable scaffolds affected cell activity and inhibited cell proliferation.(3)Antibacterial zone experiment confirmed that nano-silver PDLLA antibacterial absorbable scaffold had good antibacterial effect.With the increase of nano-silver concentration,the antibacterial effect became stronger,and it would not fail with the increase of time.(4)On the basis of not affecting the cell activity and cell proliferation,the higher the concentration of silver nanoparticles,the better the antibacterial effect will be.When the concentration of silver nanoparticles is 50 ppm,the physical properties of the scaffold,the influence on the activity of cells and the antibacterial effect are the best.