Mg-4Zn合金表面掺锶羟基磷灰石涂层：物理化学性质及体外细胞响应

The Strontium-doped hydroxyapatite coatings deposited on Mg-4Zn alloy: Physical-chemical properties and in vitro cell response

摘要:

生物可降解镁合金由于具有高比强度、低弹性模量和优良生物相容性而受到广泛关注。然而,其过高的腐蚀速率却限制了其潜在的临床应用。因此,具有高生物相容性的羟基磷灰石(HA)涂层常被用于阻碍镁基体和周围生物环境的相互作用。采用电化学沉积法在Mg-4Zn合金表面制备了HA和掺锶(Sr)HA涂层。利用扫描电子显微镜(SEM)、能谱(EDS)、透射电子显微镜(TEM)、三维激光扫描显微镜(3D LSM)和亲水角监测系统对材料表面性质进行表征。本研究还探讨了材料动态离子释放、蛋白吸附、细胞吸附、增殖与成骨分化行为。结果显示,HA中引入Sr导致了晶格畸变和结晶度下降。涂覆掺Sr HA的样品中镁离子释放量比其他样品更低,说明耐腐蚀性更好。掺Sr样品表面蛋白吸附与初始细胞吸附的改善是由于其具有更高的表面粗糙度和亲水性。Sr的引入并未显著改变细胞的增殖,却明显提高了成骨分化效果。综上所述,掺Sr HA涂层是一种非常有前景的镁合金保护性生物相容涂层。

Abstract:

Biodegradable magnesium (Mg)-based biomaterials have draw extensively attention, due to the high strength-to-weight ratio, low elastic modulus and good biocompatibility. However, the high corrosion rate is still the major obstacle for the potential clinical applications. Therefore, the highly biocompatible hydroxyapatite (HA) coatings are usually introduced to restrain the interactions between Mg-based substrate and the body fluid environment. HA and strontium (Sr)-doped HA coatings were prepared on Mg-4Zn substrates by electrochemical deposition. The surface properties of the samples were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), three-dimensional laser scanning microscopy (3D LSM) and a contact angle video system. The dynamic ion release, protein adsorption, cell adhesion, proliferation and differentiation behavior of the samples were also evaluated. The results reveal that the incorporation of Sr in the HA coatings leads to lattice distortion and decreased crystallinity. The lower amount of Mg ion release of the Sr-doped HA coated samples suggests a better corrosion resistance. The improved protein adsorption and initial adhesion of mesenchymal stem cells (MSCs) of the Sr-doped samples should be due to their higher surface roughness and wettability. The introduction of Sr leads to comparable cell proliferation behavior, but significantly improved osteogenic differentiation. It is concluded that the Sr-doped HA coatings are promising candidates for the protective biocompatible coating on Mg-based implants.