Preparation Of PLA/BG Composite Scaffold By Freeze-Drying And Its Properties

Objectives To prepare polylactic acid(PLA)/bioactive glass(BG)composite scaffolds by vacuum freeze-drying technique and study its performance.Methods The bioactive glass and polylactic acid(PLA)with a total mass of 1g were divided into four groups according to the mass ratio and mixed into a beaker,and labeled as 0%BG group,10%BG group,20%BG group and 30%BG group.The PLA powder and BG powder were put into the beaker,and the oscillator was oscillated up and down for 5 min to fully mix.After dropping 3.4ml volume 1,4-dioxane(analytical purity)and 0.6 ml dichloromethane(analytical purity)into the beaker,the mixture was stirred to a transparent solution at indoor temperature.Ultrasonic shock for 5 min,after keeping the polyethylene film sealed cup mouth quiet for 1h.It was then frozen in a refrigerator at-20 ? for 1 h.Then put in a vacuum freeze dryer and freeze-dry at-45 ? for 24 hours.Remove the residual dichloromethane by soaking in anhydrous.After the anhydrous ethanol treatment,the scaffolds materials were immersed in deionized water for 2 days.Then the PLA / BG composite scaffolds can be obtained by placing them in the electrothermal blast drying box for 24 hours.The surface morphology was detected by field emission scanning electron microscopy.The porosity of the scaffold was tested by volume method.The mechanical properties and crystal structure of the prepared scaffolds were tested by equipment such as 10,000-dimensional test machine and X-ray diffractometer.The PLA/BG composite scaffolds were immersed in simulated body fluid for 2 weeks.The elemental changes before and after immersion were analyzed by energy spectrum,and the pH values of the scaffolds were tested by pH value.MTT assay for detecting cell growth behavior of scaffold materials.Results 1 Scanning electron microscope(SEM)observation showed that both PLA and PLA/BG composite scaffolds materials had a large number of microporous structures on the inner pore walls.In the PLA/BG composite scaffolds,bioactive glass particles were dispersed in the pores and spacing of the materials,and the pore sizes were uneven.2 Porosity detection: The group containing 10%,20% BG composite scaffold materials of porosity were higher than that of the 0%BG group(P<0.05),and the 10%,20% BG scaffold materials of porosity in comparison with the porosity,the difference had statistical significance(P<0.05).3 Compressive strength test: The compressive strength of PLA/BG composite scaffold materials group were higher than that of 0%BG group(P<0.05),and the compressive strength of 20%BG composite scaffold materials group was higher than that of 10%,30% composite scaffold material groups(P<0.05).4 After 2 weeks of immersion in simulated body fluid,scanning electron microscopy(SEM)showed that PLA/BG composite scaffold had obvious hydroxyapatite formation,but no hydroxyapatite formation was found in 0%BG material.5 The results of EDS showed that the contents of Calcium,Phosphorus and Silicon of PLA/BG composite scaffolds materials were significantly different before and after immersion.The content of calcium and phosphorus of PLA/BG composite scaffolds materials after immersion were obviously lower than that before immersion,and there will be a large amount of hydroxyapatite formation in the composite scaffolds materials after immersion.At the same time,the bioactive glass was released due to the degradation of silicon in mineralization,and the content of silicon was higher than that before immersion.6 The results of MTT showed that there was no significant difference between PLA group and PLA/BG composite scaffold group(P>0.05),but there was significant difference between the positive control group(phenol group)and other groups(P<0.05).Conclusions The solvent ratio of 1,4-dioxane to methylene chloride has an effect on the porosity and compressive strength of the scaffold material.2 PLA/BG composite scaffolds with higher porosity and compressive strength can be prepared by using two solvents of 1,4 dioxin and dichloromethane,and vacuum freeze-drying.Figure20,Table6,Reference148.