Leibniz Institute for Solid State and Materials Research Dresden (IFW Dresden), Institute for Complex Materials, Helmholtzstr. 20, 01069 Dresden, Germany.
Leibniz Institute for Solid State and Materials Research Dresden (IFW Dresden), Institute for Complex Materials, Helmholtzstr. 20, 01069 Dresden, Germany.
Mater Sci Eng C Mater Biol Appl. 2020 Mar;108:110425. doi: 10.1016/j.msec.2019.110425. Epub 2019 Nov 14.
Beta-type Ti-based alloys are promising new materials for bone implants owing to their excellent mechanical biofunctionality and biocompatibility. For treatment of fractures in case of systemic diseases like osteoporosis the generation of implant surfaces which actively support the problematic bone healing is a most important aspect. This work aimed at developing suitable approaches for electrodeposition of Sr-substituted hydroxyapatite (Srx-HAp) coatings onto Ti-45Nb. Potentiodynamic polarization measurements in electrolytes with 1.67 mmol/L Ca(NO), which was substituted by 0, 10, 50 and 100% Sr(NO), and 1 mmol/L NHHPO at 333 K revealed the basic reaction steps for OH and PO formation needed for the chemical precipitation of Srx-HAp. Studies under potentiostatic control confirmed that partial or complete substitution of Ca- by Sr-ions in solution has a significant effect on the complex reaction process. High Sr-ion contents yield intermediate phases and a subsequent growth of more refined Srx-HAp coatings. Upon galvanostatic pulse-deposition higher reaction rates are controlled and in all electrolytes very fine needle-like crystalline coatings are obtained. With XRD the incorporation of Sr-species in the hexagonal HAp lattice is evidenced. Coatings formed in electrolytes with 10 and 50% Sr-nitrate were chemically analyzed with EDX mapping and GD-OES depth profiling. Only a fraction of the Sr-ions in solution is incorporated into the Srx-HAp coatings. Therein, the Sr-distribution is laterally homogeneous but non-homogeneous along the cross-section. Increasing Sr-content retards the coating thickness growth. Most promising coatings formed in the electrolyte with 10% Sr-nitrate were employed for Ca, P and Sr release analysis in Tris-Buffered Saline (150 mM NaCl, pH 7.6) at 310 K. At a sample surface: solution volume ratio of 1:200, after 24 h the amount of released Sr-ions was about 30-35% of that determined in the deposited Srx-HAp coating. In vitro studies with human bone marrow stromal cells (hBMSC) revealed that the released Sr-ions led to a significantly enhanced cell proliferation and osteogenic differentiation and that the Sr-HAp surface supported cell adhesion indicating its excellent cytocompatibility.
β 型钛基合金因其出色的机械生物功能和生物相容性而成为骨植入物的有前途的新型材料。对于治疗骨质疏松症等系统性疾病引起的骨折，生成积极支持问题骨骼愈合的植入物表面是最重要的方面。这项工作旨在开发合适的方法，用于在 Ti-45Nb 上电沉积 Sr 取代的羟基磷灰石 (Srx-HAp) 涂层。在含有 1.67 mmol/L Ca(NO₃) 的电解质中进行的动电位极化测量，其中 0、10、50 和 100%的 Sr(NO₃)取代，以及在 333 K 下的 1 mmol/L NH₄H₂PO₄，揭示了形成 Srx-HAp 的 OH 和 PO 化学沉淀所需的基本反应步骤。在恒电位控制下的研究证实，溶液中 Ca-被 Sr-离子部分或完全取代对复杂反应过程有显著影响。高 Sr 离子含量会导致中间相的形成，并随后生长出更精细的 Srx-HAp 涂层。通过恒电流脉冲沉积控制更高的反应速率，在所有电解质中都获得了非常细的针状结晶涂层。通过 XRD 证明 Sr 物种掺入六方 HAp 晶格中。用 EDX 映射和 GD-OES 深度剖析对含有 10%和 50% Sr 硝酸盐的电解质中形成的涂层进行化学分析。溶液中的 Sr 离子只有一部分被掺入 Srx-HAp 涂层中。其中，Sr 分布在横向是均匀的，但沿横截面是不均匀的。随着 Sr 含量的增加，涂层厚度的生长会减缓。在含有 10% Sr 硝酸盐的电解质中形成的最有前途的涂层被用于在 310 K 下在 Tris 缓冲盐（150 mM NaCl，pH 7.6）中进行 Ca、P 和 Sr 释放分析。在样品表面：溶液体积比为 1:200 的情况下，24 小时后释放的 Sr 离子量约为沉积 Srx-HAp 涂层中确定的 Sr 离子量的 30-35%。用人骨髓基质细胞（hBMSC）进行的体外研究表明，释放的 Sr 离子导致细胞增殖和成骨分化显著增强，Sr-HAp 表面支持细胞黏附，表明其具有优异的细胞相容性。
