| Objective:It was to explore the biocompatibility and osteogenic potential of the novel zinc-loaded chitosan/functionalized multi-walled carbon nanotube scaffold material in rat parietal defects,to evaluate the osteogenesis of zinc ion preliminarily and to obtain the optimal zinc ion concentration for promoting bone formation.Methods:Four types of chitosan/functionalized multi-walled carbon nanotube scaffolds with zinc ion concentration of 0,0.2%,1% and 2% had been prepared by solution mixing and freeze-drying method.They were labeled as gn,gl,gm and gh,respectively.The internal structure characteristics of zinc-loaded chitosan/functionalized multi-walled carbon nanotube scaffolds were investigated by scanning electron microscopy(SEM),and their surface hardness was measured by nanoindentation.MTT assay was used to detect the viability of mouse initial osteoblasts cultured with these scaffolds,and the difference of osteogenesis between different groups was preliminarily discussed.Based on the above test results,it was to determine the optimal concentration of zinc ion in scaffolds with easiness.The experimental rats were separated into four groups with randomness : GN group(parietal defects implanted with gn scaffolds),GL group(parietal defects implanted with gl scaffolds),GM group(parietal defects implanted with gm scaffolds)and GH group(parietal defects implanted with gh scaffolds).At 12 weeks after surgery,the experimental rats were executed by excessive anesthetics and cervical dislocation to obtain complete rat parietal defect bone blocks,and the gross analysis andradiological detection were conducted.Then,the parietal defect bone blocks of rats were made into tissue sections by tissue slicing technology,which were used for routine histological staining analysis such as Masson staining.Platelet-derived growth factor-BB(PDGF-BB)and bone morphogenetic protein-2(BMP-2)in rat parietal defects were analyzed via immunohistochemistry.The gray value ratio of newly formed bones was easily determined by Image Pro plus 7.0.SPSS21.0 was utilized to analyze the results via variance analysis and SNK test(P < 0.05).Results:Four groups of zinc-loaded chitosan/functionalized multi-walled carbon nanotube scaffolds were full of interconnected microporous structures with irregular pore size(177±91?m).The hardness of chitosan/carbon nanotubes scaffolds was higher than that of chitosan materials.After 24,48 and 72 h of cell inoculation,the cell proliferation rate of gm(1% zinc)group was bigger than that of the remaining three groups.In the four groups,the soft tissue grew well and had some toughness in the parietal defects.A small portion of the scaffold materials were degraded,and most of the non-absorbed materials were located in the center of the parietal defects.Low density images were displayed in the center of the round parietal defects,and high brightness density images were scattered at the defect boundary,particularly in the GM group.Tissue sections showed a large number of connective tissue formation at the boundary of the round parietal defects,while immature bone with bone lacunae was rare.The number of PDGF-BB tested by immunohistochemistry was higher than that of BMP-2.The immature bone,PDGF-BB and BMP-2 were detected more in GM group than in the remaining three groups.The gray value ratio of newly formed bone in GN,GL,GM and GH was 0.642±0.030?0.751±0.059?0.834±0.048 and 0.580±0.033,respectively.Their difference had statistic significance between groups(P<0.05).Conclusion:Zinc-loaded chitosan/functionalized multi-walled carbon nanotube scaffolds have good mechanical and osteoinductive characteristics.Furthermore,there was found that chitosan/carbon nanotubes scaffolds containing 1% zinc had the best osteogenic effect when transplanted into rat parietal defects.Altogether,the osteogenic potential of these scaffolds has not been completely developed.It is necessary to further ameliorate zinc ion concentration and optimize material composition in order to achieve better bone regeneration effect. |
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