G. RAU Inc., Scotts Valley, California.
J Biomed Mater Res B Appl Biomater. 2020 Aug;108(6):2681-2690. doi: 10.1002/jbm.b.34599. Epub 2020 Mar 11.
Nitinol is commonly used in medical implants due to its unique thermomechanical properties of shape memory and superelasticity. Free nickel has the potential to induce biological responses that may be a concern for permanent implants manufactured from nickel-containing alloys. Although there are extensive reports on the effects of surface treatments on corrosion behavior in cardiovascular Nitinol implants, there is a lack of data on corrosion resistance and impact on biocompatibility for ocular implants. Therefore, the objective of this study was to determine localized corrosion and nickel elution resistance of an electropolished Nitinol-based ocular device (Hydrus Microstent, Ivantis, Inc.) intended for patients with primary open angle glaucoma. Pitting corrosion susceptibility was characterized by potentiodynamic polarization testing per ASTM F2129. In addition, nickel ion release was quantified with immersion testing to 63 days. The results indicated high localized corrosion resistance as all samples reached polarization potentials of 800 mV without pitting initiation. Maximum nickel elution rates per device were less than approximately 1.1 ng/device/day after the first day of immersion and reduced to less than 0.1 ng/device/day after 7 days. For a patient with bilateral microstents, these nickel concentrations are ×10,000 lower than previously published tolerable intake levels for systemic toxicity. Overall, these corrosion results are in good agreement with literature values of well processed and biocompatible Nitinol devices indicating adverse systemic biological responses are not expected in vivo.
由于其形状记忆和超弹性等独特的热机械性能，镍钛诺通常用于医学植入物。游离镍有可能引起生物反应，这可能是人们对含有镍的合金制造的永久性植入物的关注。尽管有大量关于表面处理对心血管镍钛诺植入物腐蚀行为影响的报道，但关于眼内植入物的耐腐蚀性和对生物相容性的影响的数据却很少。因此，本研究的目的是确定用于原发性开角型青光眼患者的经电解抛光的基于镍钛诺的眼内装置（Hydrus Microstent，Ivantis，Inc.）的局部腐蚀和耐镍洗脱能力。点蚀敏感性通过 ASTM F2129 规定的动电位极化测试进行表征。此外，通过浸没法测试至 63 天来定量测定镍离子释放。结果表明，所有样品均达到 800 mV 的极化电位而没有点蚀起始，表现出高的局部耐腐蚀性。在浸出的第一天之后，每个装置的最大镍洗脱率均小于约 1.1ng/装置/天，在 7 天后降至小于 0.1ng/装置/天。对于双侧微支架的患者，这些镍浓度比先前发表的全身毒性可耐受摄入量低 ×10,000 倍。总体而言，这些腐蚀结果与经过良好处理和生物相容的镍钛诺装置的文献值非常吻合，表明体内不会产生不利的全身生物学反应。
