Hiromoto Sachiko, Nozoe Etsuro, Hanada Kotaro, Yoshimura Takuya, Shima Kaori, Kibe Toshiro, Nakamura Norifumi, Doi Kotaro
Research Center for Structural Materials, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba 305-0047, Japan.
Department of Oral and Maxillofacial Surgery, Field of Oral and Maxillofacial Rehabilitation, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima 890-8544, Japan.
Mater Sci Eng C Mater Biol Appl. 2021 Mar;122:111942. doi: 10.1016/j.msec.2021.111942. Epub 2021 Feb 5.
Various coatings have been developed for biodegradable Mg alloys to control the degradation speed and to improve the bone conductivity. In this study, hydroxyapatite (HAp) coatings were formed on pure Mg, Mg-0.8mass% Ca (MgCa), Mg-4mass% Y-3mass% rare earth (RE) (WE43), Mg-3mass% RE-1mass% Y (EW31) and Mg-4mass% RE (RE4) alloy rods with a chemical solution deposition method. The HAp-coated and uncoated Mg/Mg alloy rods were implanted in the femurs of rats for 3-6 months, and the corrosion suppression and bone formation abilities of the HAp coating were examined using a scanning electron microscope. The corrosion rate of WE43 was suppressed by 1/3 with the HAp coating for 6 months, and the corrosion product showed very slow dissolution. The effect of the HAp coating for pure Mg and MgCa disappeared in 1-2 months with the thinning of the rods accompanying with the obvious dissolution of the corrosion products. The effect of the HAp coating for EW31 and RE4 was not stable due to the expansion and collapse of the corrosion products. The bone formation was enhanced on the HAp layers. Eventually, the HAp coating basically suppressed the corrosion initiation and corrosion progress of Mg substrates. The magnitude of the suppression effect depended mainly on the chemical and physical stability of the corrosion products.
人们已开发出各种涂层用于可生物降解镁合金，以控制其降解速度并提高骨传导性。在本研究中，采用化学溶液沉积法在纯镁、Mg-0.8质量%钙（MgCa）、Mg-4质量%钇-3质量%稀土（RE）（WE43）、Mg-3质量%稀土-1质量%钇（EW31）和Mg-4质量%稀土（RE4）合金棒材上形成羟基磷灰石（HAp）涂层。将涂覆和未涂覆HAp的镁/镁合金棒植入大鼠股骨3至6个月，使用扫描电子显微镜检查HAp涂层的缓蚀和骨形成能力。对于WE43，HAp涂层在6个月内将腐蚀速率抑制了1/3，且腐蚀产物的溶解非常缓慢。对于纯镁和MgCa，随着棒材变细以及腐蚀产物明显溶解，HAp涂层的效果在1至2个月内消失。对于EW31和RE4，由于腐蚀产物的膨胀和塌陷，HAp涂层的效果不稳定。在HAp层上骨形成增强。最终，HAp涂层基本抑制了镁基体的腐蚀起始和腐蚀进程。抑制效果的大小主要取决于腐蚀产物的化学和物理稳定性。
