Despite many advantages of titanium, such as proper mechanical properties, biocompatibility and corrosion resistance, it has two main weaknesses; low tensile strength compared to other metallic biomaterials, and inadequate osseointegration owing to its bioinert spontaneous surface oxide layer. Grain refinement using Equal Channel Angular Pressing (ECAP) has been preferred as a desirable method to enhance low tensile strength. In addition, osseointegration could be improved by electrochemical oxidation (anodization), resulting in titania nanotubes formation on titanium surface. The latter has been extensively studied on commercially pure titanium (CP-Ti), and the formed nanotubes have been well characterized. However, a thorough observation on anodic nanotubes of ECAP-processed coarse-grained pure titanium (CG-Ti) is missing. In this research, we aimed to investigate the surface characteristics and cytotoxicity of anodic TiO₂ nanotubes on ECAP-processed CP-Ti substrate compared to that of CG-Ti. The results generally showed superior use of nanotubes anodized on ECAP-ed CP-Ti substrates over that of coarse-grained ones. We acquired ultrafine-grained titanium (UFG-Ti) by ECAP, and synthesized anodic nanotube arrays on both UFG-Ti and CG-Ti at different times and voltages. We compared the resulted nanotubes’ morphologies, physicochemical and biological properties, in which cell culture on anodic TiO₂ nanotubes of ECAP-ed CP-Ti has been performed for the first time by this research. FESEM results showed relatively lower diameter and longer nanotubes for UFG-Ti samples rather than CG-Ti ones. Nanotubes of both substrates were amorphous, and CG-Ti nanotubes were more hydrophilic than UFG-Ti nanotubes. Enhanced cell viability and proliferation were achieved on ECAP-ed CP-Ti anodic TiO₂ nanotubes.

Graphic Abstract

中文翻译：

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ECAP 对商业纯钛阳极氧化的 TiO2 纳米管物理化学和生物学特性的影响

尽管钛具有许多优点，例如适当的机械性能、生物相容性和耐腐蚀性，但它有两个主要弱点：与其他金属生物材料相比，其抗张强度较低，并且由于其生物惰性自发表面氧化层而导致骨整合不足。使用等通道角挤压 (ECAP) 进行晶粒细化已成为提高低抗拉强度的理想方法。此外，可以通过电化学氧化（阳极氧化）改善骨整合，从而在钛表面形成二氧化钛纳米管。后者已在商业纯钛 (CP-Ti) 上进行了广泛研究，并且形成的纳米管已得到很好的表征。然而，缺少对 ECAP 处理的粗粒纯钛 (CG-Ti) 阳极纳米管的彻底观察。在这项研究中，与 CG-Ti 相比，ECAP 处理的 CP-Ti 基板上的_{2 个}纳米管。结果通常表明，在 ECAP 处理的 CP-Ti 基板上阳极氧化的纳米管优于粗粒纳米管。我们通过 ECAP 获得了超细晶粒钛 (UFG-Ti)，并在不同时间和电压下在 UFG-Ti 和 CG-Ti 上合成了阳极纳米管阵列。我们比较了所得纳米管的形态、物理化学和生物学特性，其中阳极 TiO ₂上的细胞培养本研究首次实现了 ECAP 处理的 CP-Ti 纳米管。FESEM 结果显示 UFG-Ti 样品的直径相对较小且纳米管更长，而不是 CG-Ti 样品。两种基材的纳米管都是无定形的，CG-Ti 纳米管比 UFG-Ti 纳米管更亲水。在 ECAP 处理的 CP-Ti 阳极 TiO ₂纳米管上实现了增强的细胞活力和增殖。

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