Office of Science and Engineering Laboratories (OSEL), Division of Biology, Chemistry and Materials Science (DBCMS), U.S. Food and Drug Administration, Center for Devices and Radiological Health (CDRH), Silver Spring, Maryland, USA.
J Biomed Mater Res B Appl Biomater. 2024 Nov;112(11):e35495. doi: 10.1002/jbm.b.35495.
Nonabsorbable polymers used in biomedical applications are assumed to be permanently stable based on short-term testing, but some may be susceptible to oxidative degradation over several years of implantation. Traditional in vitro oxidative degradation screenings employ hydrogen peroxide (HO) solutions. However, the inherent instability of HO can compromise the consistency of oxidative conditions, especially over extended periods and at elevated temperatures used for accelerated testing. In this study, an automated reactive accelerated aging (aRAA) system, which integrates an electrochemical detection method and a feedback loop, was utilized to ensure precise control of HO concentrations during polymer oxidative degradation testing. The reproducibility of the aRAA system was evaluated by comparing four identical setups. Its efficacy as an oxidation challenge was demonstrated on (i) medical-grade vitamin E (VE) blended ultra-high molecular weight polyethylene (UHMWPE) and (ii) highly crosslinked (HXL) UHMWPE as model materials. The aRAA-aged VE-UHMWPE and HXL-UHMWPE samples were also compared against samples aged via an existing accelerated aging standard, ASTM F2003-02(2022). Samples were analyzed using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy to calculate their oxidation index per ASTM F2102-17. We observed that the aRAA system was more effective in oxidizing VE-UHMWPE and HXL-UHMWPE than the traditional ASTM F2003-02(2022) method. By providing a standardized and reliable approach to assess polymer oxidative degradation, the aRAA system could enhance the accuracy of long-term stability predictions for nonresorbable polymers in medical devices.
用于生物医学应用的不可吸收聚合物基于短期测试被假定为永久稳定，但在植入数年后，其中一些可能容易发生氧化降解。传统的体外氧化降解筛选采用过氧化氢 (HO) 溶液。然而，HO 的固有不稳定性会影响氧化条件的一致性，尤其是在延长时间和升高温度下进行加速测试时。在这项研究中，一种自动化反应加速老化 (aRAA) 系统，该系统集成了电化学检测方法和反馈回路，用于在聚合物氧化降解测试中确保 HO 浓度的精确控制。通过比较四个相同的设置评估了 aRAA 系统的重现性。通过对（i）医用级维生素 E (VE) 共混超高分子量聚乙烯 (UHMWPE) 和（ii）高度交联 (HXL) UHMWPE 作为模型材料进行氧化挑战，证明了其作为氧化挑战的有效性。还将 aRAA 老化的 VE-UHMWPE 和 HXL-UHMWPE 样品与通过现有加速老化标准 ASTM F2003-02(2022) 老化的样品进行了比较。使用衰减全反射傅里叶变换红外 (ATR-FTIR) 光谱分析样品，根据 ASTM F2102-17 计算其氧化指数。我们观察到，与传统的 ASTM F2003-02(2022) 方法相比，aRAA 系统更有效地氧化 VE-UHMWPE 和 HXL-UHMWPE。通过提供一种标准化和可靠的方法来评估聚合物氧化降解，aRAA 系统可以提高医疗器械中非吸收性聚合物长期稳定性预测的准确性。
