Dipartimento di Scienza dei Materiali e Ingegneria Chimica, Politecnico di Torino, Corso Duca degli Abruzzi, 24, 10129, Turin, Italy.
J Mater Sci Mater Med. 2011 May;22(5):1293-302. doi: 10.1007/s10856-011-4301-z. Epub 2011 Apr 2.
The in vitro corrosion behavior and biocompatibility of two Zr alloys, Zr-2.5Nb, employed for the manufacture of CANDU reactor pressure tubes, and Zr-1.5Nb-1Ta (at%), for use as implant materials have been assessed and compared with those of Grade 2 Ti, which is known to be a highly compatible metallic biomaterial. The in vitro corrosion resistance was investigated by open circuit potential and electrochemical impedance spectroscopy (EIS) measurements, as a function of exposure time to an artificial physiological environment (Ringer's solution). Open circuit potential values indicated that both the Zr alloys and Grade 2 Ti undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the aggressive environment. It also indicated that the tendency for the formation of a spontaneous oxide is greater for the Zr-1.5Nb-1Ta alloy and that this oxide has better corrosion protection characteristics than the ones formed on Grade 2 Ti or on the Zr-2.5Nb alloy. EIS study showed high impedance values for all samples, increasing with exposure time, indicating an improvement in corrosion resistance of the spontaneous oxide film. The fit obtained suggests a single passive film presents on the metals surface, improving their resistance with exposure time, presenting the highest values to the Zr-1.5Nb-1Ta alloy. For the biocompatibility analysis human osteosarcoma cell line (Saos-2) and human primary bone marrow stromal cells (BMSC) were used. Biocompatibility tests showed that Saos-2 cells grow rapidly, independently of the surface, due to reduced dependency from matrix deposition and microenvironment recognition. BMSC instead display a reduced proliferation, possibly caused by a reduced crosstalk with the metal surface microenvironment. However, once the substrate has been colonized, BMSC seem to respond properly to osteoinduction stimuli, thus supporting a substantial equivalence in the biocompatibility among the Zr alloys and Grade 2 titanium. In summary, high in vitro corrosion resistance together with satisfactory biocompatibility make the Zr-2.5Nb and Zr-1.5Nb-1Ta crystalline alloys promising biomaterials for surgical implants.
两种用于制造 CANDU 反应堆压力管的 Zr 合金，Zr-2.5Nb 和 Zr-1.5Nb-1Ta（at%），以及作为植入材料的 Grade 2 Ti 的体外腐蚀行为和生物相容性已被评估，并与已知的高度相容的金属生物材料进行了比较。通过开路电位和电化学阻抗谱（EIS）测量研究了体外耐腐蚀性，作为暴露于人工生理环境（Ringer 溶液）时间的函数。开路电位值表明，两种 Zr 合金和 Grade 2 Ti 由于在腐蚀性环境中自发形成的氧化膜钝化金属表面而发生自发钝化。这也表明，Zr-1.5Nb-1Ta 合金形成自发氧化物的趋势更大，并且该氧化物比在 Grade 2 Ti 或 Zr-2.5Nb 合金上形成的氧化物具有更好的腐蚀保护特性。EIS 研究表明，所有样品的阻抗值都很高，随着暴露时间的增加而增加，表明自发氧化膜的耐腐蚀性得到了提高。拟合结果表明，金属表面存在单一的钝化膜，随着暴露时间的增加提高了其电阻，Zr-1.5Nb-1Ta 合金的电阻值最高。对于生物相容性分析，使用了人骨肉瘤细胞系（Saos-2）和人原代骨髓基质细胞（BMSC）。生物相容性测试表明，Saos-2 细胞由于对基质沉积和微环境识别的依赖性降低而快速生长，与表面无关。BMSC 相反，增殖减少，可能是由于与金属表面微环境的交流减少所致。然而，一旦基质被殖民化，BMSC 似乎对成骨诱导刺激做出适当反应，从而支持 Zr 合金和 Grade 2 钛之间在生物相容性方面的实质性等同。总之，高体外耐腐蚀性和令人满意的生物相容性使 Zr-2.5Nb 和 Zr-1.5Nb-1Ta 多晶合金成为有前途的外科植入物生物材料。
