| Interconnectivity and mechanical properties of bone tissue engineering scaffolds plays a very important role in biological performance in vivo.Porous scaffolds play the role in supporting cell adhesion,proliferation,differentiation and tissue growth in the process of bone tissue repair or replacement.Scaffolds play the role of matrix in bone tissue engineering,provide a suitable place for the normal physiological activity of cells and the growth of tissue.Titanium and its alloys have been widely used in the process of bone tissue repair because of their excellent physical and chemical properties and high mechanical strength.However,a major concern with titanium implants is their weak ability of inducing bone tissue growth due to the biological inertia of titanium implants.One approach to resolving the problem is to be modified of the surface of titanium,which can improve the biological properties.Studies suggest that the special surface micro-and nano-structures can promote cell adhesion and cell growth.Thus,it is necessary to study the construction of special micro-nanostructures on the surface of porous titanium scaffold.This study was based on the porous titanium scaffolds,the surface was modified by pretreatment,and then the electrochemical deposition was used to construct hydroxyapatite(HA)coating with micro-nano structure.The effects of different pulse voltage and deposition time on the growth of micro-nano structure on the surface of titanium scaffolds.We also studied the effect on cell adhesion,proliferation and differentiation of the surface micro-nano structure.The main contents and results are as follows:The titanium powder was used for preparing highly interconnected porous scaffolds by sugar spheres agent and gel-casting methods.The effects of Ti concentration on porosity,shrinkage,macrospore size and compressive strength of the scaffolds were investigated.The results show that the Ti-50 scaffold has relatively excellent pore structure and compressive strength.However,Ti-30 scaffold is prone to collapse in the sintering process,and Ti-70 scaffold will make the pore of the scaffold more closed.The effects of different drying methods on the shrinkage rate and mass reduction rate of the Ti-50 scaffold were also investigated.The results showed that after freeze-drying,the Ti-50 scaffolds were more favorable to maintain the morphology than after natural drying method.Construction of different surface microstructures on Ti-50 porous scaffolds were obtained by pretreatment of alkali heat treatment and dopamine immersion.We studied the effect of different surface structure on the formation of HA coating by electrochemical deposition.We also studied the effects of different pulse voltage and deposition time on the growth of micro-nano structure on the surface of alkali heat poro titanium scaffolds.The results showed that under the condition of pulse voltage of-1.0 V and deposition time of 60 min,a homogeneous micro-nano HA coating was obtained on the surface of alkali heat titanium scaffolds.During the compression strength test,we chose the scaffolds with a depth-diameter aspect ratio of 3:2.The results showed that surface microstructures had less obvious effects on the scaffolds' compressive strength.The extraction assay for cytotoxicity test showed that the scaffolds were non-cytotoxicity to BMSCs and had good biocompatibility.Scaffolds were co-cultured with BMSCs for cell adhesion and proliferation experiments.The proliferation of BMSCs on scaffolds with surface microstructures don't have obviously differences.ALP expression experiments showed that alkali heat scaffold and deposition of HA coating on alkali heat scaffolds could promote the differentiation of BMSCs into osteoblasts,which indicates the micro-nanostructure on surface of scaffolds can affect the performance of BMSCs differentiation. |
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