应力对D,L-聚乳酸泡沫衬垫降解的影响研究

Studies on the Effect of Continuous Stress on the Degradation of Poly(D,L-lactic acid) Foam-gasket

利用自行研制的力学加载装置,详细研究了持续应力载荷对初始相对分子量为2.0×105的D,L-聚乳酸(poly(D,L-lactic acid),PDLLA)泡沫衬垫材料的体外降解行为的影响。PDLLA材料在37℃、pH值为7.4的PBS溶液中的降解行为通过表面形貌、相对分子量、弹性模量、抗拉强度、失重百分率等指标进行表征。三个月的降解结果表明受载荷的实验组降解速率明显快于空载的对照组,其中实验组中拉应力和复合应力对PDLLA降解的影响大于压应力。由此可知,PDLLA在生物体内的降解不仅受所处局部体液环境影响,还将受周围应力环境影响。综合考虑PDLLA降解所受应力影响,将有助于控制膜垫降解速率,从而使其降解速率有望与骨愈合速率一致。

The effect of continuous stress on the degradation rate of poly（ D, L-lactic acid） （PDLLA） foam-gasket with initial molecular weight as 2.0 ×10^5 was investigated in detail by the self-made stress-loading device. The degradation behaviors of PDLLA in the PBS solution （pH, 7.4） at 37℃ were evaluated with the changes of surface morphology, molecular weight, elastic modulus, tensile strength and mass loss. The results revealed that the degradation rate of PDLLA under continuous stress loadings for 3 months were obviously quicker than those of without stress-loading. The influences of tensile stress and combined stress were greater than that of compressive stress. It was indicated that the in vivo degradation of PDLLA would not only be influenced by the local solution, but also by the surrounding stress circumstance. Therefore one can design the degradation rate of PDLLA with that of bone healing by considering the loading stress when implanted.