| Objectives Polylactic acid/Hydroxyapatite porous scaffolds were prepared by freezedrying method,and their surface morphology,porosity,compressive strength and cytotoxicity were tested to provide experimental basis for tissue engineering research.Methods Experiment 1 Polylactic acid porous scaffolds were prepared by vacuum freeze-drying method.0.5 g PLA was dried for 24 hours and dissolved in 4 ml organic solvent(1,4-dioxane/dichloromethane,v/v).According to the volume ratio of organic solvent(1,4-dioxane/dichloromethane,v/v),PLA was divided into three groups(n=5): group A: 95/5;group B: 90/10;group C: 85/15.PLA porous scaffolds were obtained after drying in vacuum freeze-drying chamber for 24 hours.The surface morphology was observed by scanning electron microscope(SEM),the porosity was measured by volumetric method,the compressive strength was tested by universal testing machine and the cytotoxicity was tested by MTT method.All the data were analyzed by SPSS17.0 statistical software,and the level of statistical test was set at P<0.05 with statistical difference.Experiment 2 According to the volume ratio of the organic solution in the group C PLA scaffold material with the best comprehensive value prepared in Experiment 1,the PLA and n HA were mixed with the organic solvent(1,4-dioxane / dichloromethane,v/v)in proportion,the PLA/n HA composite porous scaffolds containing n HA were prepared by vacuum freeze-drying technology.According to the content of n HA,there were divided into 4 groups(n=5): group A: 5% n HA;group B: 10% n HA;group C 15% n HA;group D: 20% n HA.The surface morphology was observed by SEM,the porosity was measured by volumetric method,the compressive strength was tested by universal testing machine,and the cytotoxicity was tested by MTT method.All the data were analyzed by SPSS17.0 statistical software,and the level of statistical test was set at P<0.05 with statistical difference.Results 1 The polylactic acid porous scaffold material prepared by vacuum freeze-drying technique shows pore structure with different sizes under the SEM.The pore size is between 10?m and 200?m,and the pore connectivity is good.The specimens of group A showed that the pores were mainly oblong and circular structures under the SEM,the pore sizes were different and the pores were dense,but there were closed pores;The test specimens of group B showed that the holes were mainly elliptical under the SEM;The specimens of group C showed that there were many small holes on the wall of the large holes under the SEM,and the walls of the holes were rough.The results of porosity test showed that the porosity of PLA porous scaffolds prepared by freeze-drying method ranged from(68.97±0.12)% to(73.75±0.48)%,and there were significant differences between the two groups(P<0.05).The results of compressive strength test showed that the average compressive strength of PLA porous scaffolds ranged from(2.90±0.53)MPa to(4.11±0.05)MPa,and there were significant differences between the two groups(P< 0.05).The cytotoxicity test showed that the cells in the negative control group and the experimental group proliferated well during the observation period of 1,3,and 5 days,and the cells of the positive control group hardly increased.There were significant difference between negative control group and positive control group(P<0.05),but there were no significant difference between the negative control group and the experimental group(P> 0.05).The results showed that the scaffold material did not show any toxicity to cell proliferation and met the requirements of cytotoxicity test in vitro.2 The PLA/n HA composite scaffolds prepared by freeze-drying method can be seen under the SEM that the PLA/n HA composite scaffolds prepared by adding n HA have similar pore structure with pure PLA scaffolds and good pore connectivity,however,with the addition of n HA,the number of micropores in scaffolds decreased,and even some macropores decreased with the increase of n HA content,this may be due to the agglomeration of n HA content which occupies part of the space of the scaffold material.The results of porosity test showed that the porosity of composite scaffolds were from(64.30±0.65)% to(71.34±0.34)%,and it tended to decrease with the increase of n HA content.The results of compressive strength showed that the average compressive strength of PLA/n HA composite scaffolds was from(3.20±0.09)MPa to(4.29±0.08)MPa,and there was significant difference between the two groups(P<0.05),which met the requirements of the compressive strength of cancellous bone.The cytotoxicity test showed that the cells in the experimental group proliferated well during the observation period of 1,3,and 5 days,and the cells in the positive control group hardly increased.The difference between the experimental group and the positive control group was statistically significant(P<0.05).Conclusions 1 Under the experimental conditions,PLA scaffolds prepared by freezedrying method have interconnected pore structure,and the compressive strength of cancellous bone is in the range of compressive strength.Cytotoxicity test results show that PLA scaffolds have good cell compatibility.2 Under the experimental conditions,the PLA/n HA composite scaffolds prepared by vacuum freeze-drying method have different pores inside,and the connectivity between the pores is good.With the increase of n HA content,the compressive strength of PLA/n HA composite scaffolds increases first and then decreases.The compressive strength of PLA/n HA composite scaffolds is the highest when n HA content is 15%,which is within the compressive strength range of bone tissue.With the increase of n HA content,the compressive strength of PLA/n HA composite scaffolds increases first and then decreases.The compressive strength of PLA/n HA composite scaffolds is the highest when n HA content is 15%,which is within the range of compressive strength of cancellous bone.The cytotoxicity test results showed that the PLA/n HA composite scaffold material was non-toxic.Figure10;Table8;Reference 146... |
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