College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, PR China; Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong Kong, China; Shenzhen Key Laboratory for Innovative Technology in Orthopaedic Trauma, The University of Hong Kong Shenzhen Hospital, 1 Haiyuan 1st Road, Futian District, Shenzhen, China.
School of Materials Science & Engineering, the Key Laboratory of Advanced Ceramics and Machining Technology by the Ministry of Education of China, Tianjin University, Tianjin 300072, China.
Acta Biomater. 2019 Nov;99:495-513. doi: 10.1016/j.actbio.2019.09.008. Epub 2019 Sep 10.
Magnesium biometals exhibit great potentials for orthopeadic applications owing to their biodegradability, bioactive effects and satisfactory mechanical properties. However, rapid corrosion of Mg implants in vivo combined with large amount of hydrogen gas evolution is harmful to bone healing process which seriously confines their clinical applications. Enlightened by the superior biocompatibility and corrosion resistance of passive titanium oxide layer automatically formed on titanium alloy, we employ the Ti and O dual plasma ion immersion implantation (PIII) technique to construct a multifunctional TiO based nano-layer on ZK60 magnesium substrates for enhanced corrosion resistance, osteoconductivity and antimicrobial activity. The constructed nano-layer (TiO/MgO) can effectively suppress degradation rate of ZK60 substrates in vitro and still maintain 94% implant volume after post-surgery eight weeks. In animal study, a large amount of bony tissue with increased bone mineral density and trabecular thickness is formed around the PIII treated group in post-operation eight weeks. Moreover, the newly formed bone in the PIII treated group is well mineralized and its mechanical property almost restores to the level of that of surrounding mature bone. Surprisingly, a remarkable killing ratio of 99.31% against S. aureus can be found on the PIII treated sample under ultra-violet (UV) irradiation which mainly attributes to the oxidative stress induced by the reactive oxygen species (ROS). We believe that this multifunctional TiO based nano-layer not only controls the degradation of magnesium implant, but also regulates its implant-to-bone integration effectively. STATEMENT OF SIGNIFICANCE: Rapid corrosion of magnesium implants is the major issue for orthopaedic applications. Inspired by the biocompatibility and corrosion resistance of passive titanium oxide layer automatically formed on titanium alloy, we construct a multifunctional TiO/MgO nanolayer on magnesium substrates to simultaneously achieve superior corrosion resistance, satisfactory osteoconductivity in rat intramedullary bone defect model and excellent antimicrobial activity against S. aureus under UV irradiation. The current findings suggest that the specific TiO/MgO nano-layer on magnesium surface can achieve the three objectives aforementioned and we believe this study can demonstrate the potential of biodegradable metals for future clinical applications.
镁生物金属由于其生物降解性、生物活性效应和令人满意的机械性能，在骨科应用中具有巨大的潜力。然而，镁植入物在体内的快速腐蚀与大量氢气的产生对骨愈合过程有害，严重限制了它们的临床应用。受钛合金表面自动形成的具有优异生物相容性和耐腐蚀性的氧化钛层的启发，我们采用 Ti 和 O 双等离子体离子注入（PIII）技术在 ZK60 镁基体上构建了一种多功能 TiO 基纳米层，以提高耐腐蚀性、骨诱导性和抗菌活性。构建的纳米层（TiO/MgO）可有效抑制 ZK60 基体在体外的降解速率，在术后 8 周仍保持 94%的植入物体积。在动物研究中，在术后 8 周时，大量骨组织形成，骨密度和小梁厚度增加。此外，在 PIII 处理组中，新形成的骨得到很好的矿化，其机械性能几乎恢复到周围成熟骨的水平。令人惊讶的是，在紫外线（UV）照射下，PIII 处理的样品对金黄色葡萄球菌的杀灭率高达 99.31%，这主要归因于活性氧（ROS）引起的氧化应激。我们相信，这种多功能 TiO 基纳米层不仅可以控制镁植入物的降解，还可以有效地调节其与骨的整合。
镁植入物的快速腐蚀是骨科应用的主要问题。受钛合金表面自动形成的具有生物相容性和耐腐蚀性的氧化钛层的启发，我们在镁基体上构建了一种多功能 TiO/MgO 纳米层，以同时实现优异的耐腐蚀性、在大鼠髓内骨缺损模型中令人满意的骨诱导性和在 UV 照射下对金黄色葡萄球菌的优异抗菌活性。目前的研究结果表明，镁表面的特定 TiO/MgO 纳米层可以实现上述三个目标，我们相信这项研究可以展示可生物降解金属在未来临床应用中的潜力。
