Introduction: Despite great progress made in developing orthopedic implants, the development of titanium (Ti) implants with ideal early osseointegration remains a big challenge. Our pilot study has demonstrated that Si-TiO₂ nanotubes on the surface of Ti substrates could enhance their osteogenic activity. Hence, in this study, we aim to comprehensively evaluate the effects of silicon-doped titania (Si-TiO₂) nanotubes on the osseointegration property of Ti implants.
Materials and Methods: The Ti implants were surface modified with Si-TiO₂ nanotubes through in situ anodization and Si plasma immersion ion implantation (PIII) method. Three groups were divided as Ti implants (Ti), Ti modified with TiO₂ nanotubes (TiO₂-NTs) and Ti modified with Si-TiO₂ nanotubes (Si-TiO₂-NTs). The morphology of Si-TiO₂ nanotubes was observed by scanning electron microscope. The growth and osteogenic differentiation of MC3T3-E1 cells on the Ti implants were evaluated. Further, the pull-out tests and in vivo osseointegration ability evaluation were performed after implanting the screws in the femur of Sprague Dawley rats.
Results: The Si-TiO₂ nanotubes could be seen on the surface of Ti implants. The MC3T3-E1 cells could grow on the surface of Ti, TiO₂-NTs and Si-TiO₂-NTs, and showed fast proliferation rate on the Si-TiO₂-NTs. Moreover, the production of some osteogenesis-related proteins (ALP and Runx2) at one week and calcium deposition at four week was also enhanced in Si-TiO₂-NTs rather than other groups. In vivo osseointegration results showed that Si-TiO₂ nanotube-modified Ti screws had higher pullout force at two and four weeks as well as enhanced new bone formation at six weeks compared to bare Ti screws and Ti screws modified with TiO₂ nanotubes alone.
Discussion: The modification of Si-TiO₂-NTs on the Ti substrate could generate a nanostructured and hydrophilic surface, which can promote cell growth. Moreover, the existence of the TiO₂ nanotubes and Si element also can improve the in vitro osteogenic differentiation of MC3T3-E1 cells and early bone formation around the implanted screws. Together, findings from this study show that surface modification of Ti implants with Si-TiO₂ nanotubes could enhance early osseointegration and therefore has the potential for clinical applications.

Keywords: osseointegration, implant, silicon, titanium dioxide, nanotubes


中文翻译：

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硅掺杂二氧化钛纳米管表面改性增强钛植入物的骨整合

简介：尽管在开发骨科植入物方面取得了很大进展，但具有理想早期骨整合的钛 (Ti) 植入物的开发仍然是一个巨大的挑战。我们的初步研究表明，Ti 基材表面的Si-TiO _{2纳米管可以增强其成骨活性。}因此，在本研究中，我们旨在全面评估硅掺杂二氧化钛（Si-TiO ₂）纳米管对钛植入物骨整合性能的影响。
材料与方法： Ti 植入物采用Si-TiO ₂纳米管通过原位阳极氧化和Si 等离子体浸没离子注入(PIII) 方法进行表面改性。三组被分为钛植入物（Ti），用TiO _2修饰的Ti纳米管(TiO ₂ -NTs)和用Si-TiO ₂纳米管(Si-TiO ₂ -NTs)改性的Ti。采用扫描电镜观察Si-TiO _{2纳米管的形貌。}评估了钛植入物上 MC3T3-E1 细胞的生长和成骨分化。此外，在将螺钉植入 Sprague Dawley 大鼠的股骨后进行了拔出试验和体内骨整合能力评估。
结果：在Ti植入物表面可以看到Si-TiO _{2纳米管。}MC3T3-E1细胞可以在Ti、TiO ₂ -NTs和Si-TiO _{2 -NTs表面生长，并且在Si-TiO 2}上表现出较快的增殖速度。-NT。_{此外，与其他组相比，Si-TiO 2} -NTs在一周内某些成骨相关蛋白（ALP 和 Runx2）的产生和四周时的钙沉积也有所增加。体内骨整合结果表明，与裸钛螺钉和仅用TiO _{2纳米管改性的钛螺钉相比，Si-TiO 2纳米管改性的钛螺钉在第 2 周和第 4 周时具有更高的拔出力，并且在第 6 周时新骨形成增强。}讨论：在Ti基底上修饰Si-TiO ₂ -NTs可以产生纳米结构的亲水表面，从而促进细胞生长。此外，TiO _2的存在
纳米管和硅元素还可以改善 MC3T3-E1 细胞的体外成骨分化和植入螺钉周围的早期骨形成。总之，这项研究的结果表明，用 Si-TiO ₂纳米管对 Ti 植入物进行表面改性可以增强早期骨整合，因此具有临床应用的潜力。

关键词：骨整合，植入物，硅，二氧化钛，纳米管