Kannan M Bobby, Walter R, Yamamoto A
Biomaterials and Engineering Materials (BEM) Laboratory, College of Science, Technology and Engineering, James Cook University, Townsville, Queensland 4811, Australia.
Biometals Group, International Centre for Materials Nanoarchitectonics, National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044, Japan.
ACS Biomater Sci Eng. 2016 Jan 11;2(1):56-64. doi: 10.1021/acsbiomaterials.5b00343. Epub 2015 Dec 7.
Calcium phosphate (CaP) was electrochemically coated on a magnesium-calcium (Mg-Ca) alloy using an unconventional electrolyte and a pulse-potential method. The CaP particles of the coating were relatively large, flat, and irregularly oriented; however, they covered the entire alloy surface with a coating thickness of 5 μm. Cytocompatibility tests using L929 cells inoculated in Eagle minimum essential medium supplemented with 10% (v/v) fetal bovine serum (E-MEM+FBS) revealed that CaP coating improved the cytocompatibility of the alloy. It also showed effective suppression of Mg ion release from the substrate of the coated alloy and consequently reduced the pH increase of the medium. In vitro degradation experiments using electrochemical techniques in simulated body fluid (SBF) also suggested significant enhancement of the alloy degradation resistance by CaP coating. Potentiodynamic polarization results showed that the corrosion current density of the coated alloy was ∼95% lower than that of the bare metal. Electrochemical impedance spectroscopy results revealed that the polarization resistance () of the coated alloy was more than an order of magnitude higher than that of the bare metal after 2 h of immersion in SBF. Interestingly, after 72 h of immersion, the measured had decreased by ∼82%, and the coating appeared cracked and damaged. The results suggest that SBF is more aggressive than E-MEM+FBS cell culture medium.
采用非常规电解液和脉冲电位法在镁钙（Mg-Ca）合金上电化学涂覆磷酸钙（CaP）。涂层的CaP颗粒相对较大、扁平且取向不规则；然而，它们以5μm的涂层厚度覆盖了整个合金表面。使用接种于补充有10%（v/v）胎牛血清的伊格尔最低限度基本培养基（E-MEM+FBS）中的L929细胞进行的细胞相容性测试表明，CaP涂层改善了合金的细胞相容性。它还显示出有效抑制了涂覆合金基体中镁离子的释放，从而降低了培养基的pH值升高。在模拟体液（SBF）中使用电化学技术进行的体外降解实验也表明，CaP涂层显著提高了合金的耐降解性。动电位极化结果表明，涂覆合金的腐蚀电流密度比裸金属低约95%。电化学阻抗谱结果显示，在SBF中浸泡2小时后，涂覆合金的极化电阻（）比裸金属高一个数量级以上。有趣的是，浸泡72小时后，测得的极化电阻下降了约82%，涂层出现裂纹和损坏。结果表明，SBF比E-MEM+FBS细胞培养基更具侵蚀性。
