Schubert M A, Wiggins M J, Anderson J M, Hiltner A
Department of Macromolecular Science, Case Western Reserve University, Cleveland, Ohio 44106, USA.
J Biomed Mater Res. 1997 Mar 15;34(4):519-30. doi: 10.1002/(sici)1097-4636(19970315)34:4<519::aid-jbm12>3.0.co;2-7.
It is generally accepted that biodegradation of poly(etheruethane urea) (PEUU) involves oxidation of the polyether segments on the surface where leukocytes are adhered. The influence of dissolved oxygen, which is known to control oxidation of polymers in more traditional environments, was explored in this study. Specimens treated in vitro with hydrogen peroxide-cobalt chloride for 12 days exhibited a brittle, degraded surface layer about 10 microm thick. Attenuated total reflectance-Fourier transform infrared spectroscopy of the surface revealed that the ether absorbance at 1110 cm(-1) gradually decreased with in vitro treatment time to 30% of its initial value after 12 days. In contrast, 6 days in vitro followed by 6 days in air produced a decrease to 12% of the initial volume. Therefore, removing a specimen from the in vitro solution after 6 days and exposing it to air for the remainder of the 12 days actually resulted in more oxidation than leaving it in the in vitro solution for the entire 12 days. These results suggest that PEUU degrades by an autooxidation mechanism sustained by oxygen. By successfully modeling the depth of the surface degraded layer with a diffusion-reaction model, it was demonstrated that PEUU biodegradation is controlled by diffusion of oxygen into the polymer.
普遍认为，聚（醚脲乙烷）（PEUU）的生物降解涉及白细胞粘附表面上聚醚链段的氧化。本研究探讨了溶解氧的影响，已知溶解氧在更传统的环境中控制聚合物的氧化。体外用过氧化氢 - 氯化钴处理12天的标本呈现出约10微米厚的脆性降解表面层。表面的衰减全反射 - 傅里叶变换红外光谱显示，在1110 cm(-1)处的醚吸光度随着体外处理时间逐渐降低，12天后降至其初始值的30%。相比之下，体外6天然后在空气中放置6天导致吸光度降至初始值的12%。因此，在6天后将标本从体外溶液中取出并在剩余的12天中将其暴露于空气中，实际上比将其在体外溶液中放置整个12天导致更多的氧化。这些结果表明，PEUU通过由氧气维持的自动氧化机制降解。通过用扩散 - 反应模型成功模拟表面降解层的深度，证明了PEUU的生物降解受氧气向聚合物中的扩散控制。
