Stachelek Stanley J, Alferiev Ivan, Choi Hoon, Chan Chun Wai, Zubiate Brett, Sacks Michael, Composto Russell, Chen I-Wei, Levy Robert J
Division of Cardiology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104-4318, USA.
J Biomed Mater Res A. 2006 Sep 15;78(4):653-61. doi: 10.1002/jbm.a.30828.
Polyurethane (PU) components of cardiovascular devices are subjected to oxidation-initiated surface degradation, which leads to cracking and ultimately device failure. In the present study, we investigated a novel bromoalkylation chemical strategy to covalently attach the antioxidant, di-tert-butylphenol (DBP), and/or cholesterol (Chol) to the PU urethane nitrogen groups to hypothetically prevent oxidative degradation. These experiments compared PU, PU-DBP, PU-Chol, and PU-Chol-DBP. A series of comparative oxidative degradation studies involved exposing PU samples (modified and unmodified) to H2O2-CoCl2 for 15 days at 37 degrees C, to cause accelerated oxidative degradation. The extent and effects of degradation were assessed by attenuated total reflectance Fourier transformation infrared spectroscopy (FTIR), scanning electron microscopy (SEM), surface contact angle measurements, and mechanical testing. Both the Chol and DBP modification conferred significant resistance to oxidation related changes compared to unmodified PU per FTIR and SEM results. SEM demonstrated cavitation only in unmodified PU. However, contact angle analysis showed significant oxidation-induced changes only in the Chol-modified PU formulations. Most importantly, uniaxial stress-strain testing revealed that only PU-DBP demonstrated bulk elastomeric properties that were minimally affected by oxidation; PU, PU-Chol, PU-Chol-DBP showed marked deterioration of their stress-strain properties following oxidation. In conclusion, these results demonstrate that derivatizing PU with DBP confers significant resistance to oxidative degradation compared with unmodified PU.
心血管装置的聚氨酯（PU）部件会遭受氧化引发的表面降解，这会导致开裂并最终致使装置失效。在本研究中，我们探究了一种新型的溴烷基化化学策略，将抗氧化剂二叔丁基苯酚（DBP）和/或胆固醇（Chol）共价连接到PU聚氨酯氮基团上，以假设性地防止氧化降解。这些实验对PU、PU-DBP、PU-Chol和PU-Chol-DBP进行了比较。一系列比较性氧化降解研究包括将PU样品（改性和未改性）在37℃下暴露于H2O2-CoCl2中15天，以引发加速氧化降解。通过衰减全反射傅里叶变换红外光谱（FTIR）、扫描电子显微镜（SEM）、表面接触角测量和力学测试来评估降解的程度和影响。根据FTIR和SEM结果，与未改性的PU相比，Chol和DBP改性都赋予了显著的抗氧化相关变化的抗性。SEM显示只有未改性的PU出现了空化现象。然而，接触角分析表明只有Chol改性的PU配方出现了显著的氧化诱导变化。最重要的是，单轴应力-应变测试表明只有PU-DBP表现出基本不受氧化影响的本体弹性体性能；PU、PU-Chol、PU-Chol-DBP在氧化后其应力-应变性能出现了明显恶化。总之，这些结果表明，与未改性的PU相比，用DBP衍生化PU可赋予其显著的抗氧化降解能力。
