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):493-505. doi: 10.1002/(sici)1097-4636(19970315)34:4<493::aid-jbm10>3.0.co;2-e.
Vitamin E (+/-alpha-tocopherol) was recently investigated as an antioxidant for implanted poly(etherurethane urea) (PEUU) elastomers. In that work, vitamin E prevented chemical degradation of biaxially strained PEUU up to 5 weeks implantation, and prevented pitting and cracking of the PEUU surface for the duration of the 10-week cage implant study. The promising results of the in vivo studies motivated a detailed comparison of vitamin E with Santowhite, the standard antioxidant used in PEUU elastomers. To evaluate vitamin E and Santowhite as antioxidants in PEUU, an accelerated in vitro treatment system was used that mimics the in vivo degradation of PEUUs. Vitamin E was even more effective than Santowhite in preventing pitting and cracking to the biaxially strained PEUU elastomers. The inhibition of ether oxidation was greater with vitamin E than with Santowhite when compared by equivalent concentrations and molar concentrations, respectively. It is hypothesized that the increased effectiveness of vitamin E in this system, compared to Santowhite, is due to differences in antioxidant mechanism(s). Vitamin E is more efficient in preventing PEUU oxidation than Santowhite because its phenoxy radical is more stable and it can terminate more than one chain per vitamin E molecule.
维生素E（±α-生育酚）最近被作为植入聚醚聚氨酯脲（PEUU）弹性体的抗氧化剂进行了研究。在该研究中，维生素E在长达5周的植入期内防止了双轴拉伸PEUU的化学降解，并在为期10周的笼式植入研究期间防止了PEUU表面出现点蚀和开裂。体内研究的这些有前景的结果促使对维生素E与PEUU弹性体中使用的标准抗氧化剂Santowhite进行详细比较。为了评估维生素E和Santowhite在PEUU中的抗氧化性能，使用了一种模拟PEUUs体内降解的加速体外处理系统。在防止双轴拉伸PEUU弹性体出现点蚀和开裂方面，维生素E甚至比Santowhite更有效。当分别按等效浓度和摩尔浓度比较时，维生素E对醚氧化的抑制作用比Santowhite更强。据推测，与Santowhite相比，维生素E在该系统中有效性的提高是由于抗氧化机制的差异。维生素E在防止PEUU氧化方面比Santowhite更有效，因为其苯氧基自由基更稳定，且每个维生素E分子可以终止不止一条链。
