The Research On The Preparation And Modification Of Phosphate-borate Glass Ceramic Porous Scaffolds

Nowadays, many materials have been used to prepare the bone tissue engineering scaffolds. The bioactive glasses have become one of the research focuses due to its bone conductivity and binding ability. Since the silicate bioglass such as 45S5 glass can not degrade completely in vivo and transform to the similar materials as human bone, which limits the application of the silicate bioglass.In order to solve the above problems, a novel borate glass ceramic containingβ-NaCaPO4 is prepared. Porous scaffolds are prepared from particles sized 300-400um and 200-300μm by sintering and binding method respectively. The effect of preparation process on bioactivity of scaffolds is studied. Poly(lactic acid), chitosan and starch are coated on the sintered scaffolds by immersion method and the effect on bioactivity is also analyzed. Sodium silicate and chitosan are used as binding agent to prepare the binding scaffolds.45S5 glass scaffolds are prepared as comparison.The results present that the bioactivity of the borate glass ceramic scaffolds is much better than that of the 45S5 glass scaffolds. The bioactivity of the binding scaffolds is much better than that of the sintering scaffolds. As the binding agent, the chitosan can control the scaffolds'velocity and maintain the strength of the scaffolds in practice. After immersing in the SBF solution for 28 days, the weight loss of the sodium silicate binding scaffolds is 71.12% and the chitosan binding scaffolds is 66.12%, the weight loss of the sintering scaffolds is 50.53%, meantime, the weight loss of the three types of 45S5 glass scaffolds is 20.89%,6.26% and 6.68% respectively. The results are proven by the XRD, FTIR and SEM patterns. The. glass phase in the borate glass ceramic degrades rapidly and the crystal phase ofβ-NaCaPO4 degrades slowly, which can ensure the strength in the late period of degradation. Polymer coatings can contral the degradation velocity of the scaffolds during the middle period of the degradation, which is benefit to ensure the strength of the scaffolds in application environment. The bioactivities of the scaffolds are related to the groups on the coating polymers. The starch coated scaffolds have the best bioactivity, the next are chitosan coated scaffolds, last are PLA coated scaffolds. The bioactivities of coated 45S5 scaffolds obey the same way.The result of cytoxicity tests and cells appearance observation reveals that the PLA coated scaffolds have the best biocompatibility in the MTT test, but the least cells adherence on the surfaces. The starch coated scaffolds have the best biocompatibility.