Institute for Frontier Materials, Deakin University , Burwood, Victoria 3125, Australia.
ACS Appl Mater Interfaces. 2014;6(21):18989-97. doi: 10.1021/am506825d. Epub 2014 Oct 28.
Mg alloys are attractive candidate materials for biodegradable stents. However, there are few commercially available Mg-based stents in clinical use because Mg alloys generally undergo rapid localized corrosion in the body. In this study, we report a new surface coating for Mg alloy AZ31 based on a low-toxicity ionic liquid (IL), tributyl(methyl)phosphonium diphenyl phosphate (P1,4,4,4 dpp), to control its corrosion rate. Emphasis is placed on the effect of treatment temperature. We showed that enhancing the treatment temperature provided remarkable improvements in the performances of both corrosion resistance and biocompatibility. Increasing treatment temperature resulted in a thicker (although still nanometer scale) and more homogeneous IL film on the surface. Scanning electron microscopy and optical profilometry observations showed that there were many large, deep pits formed on the surface of bare AZ31 after 2 h of immersion in simulated body fluid (SBF). The IL coating (particularly when formed at 100 °C for 1 h) significantly suppressed the formation of these pits on the surface, making corrosion occur more uniformly. The P1,4,4,4 dpp IL film formed at 100 °C was more hydrophilic than the bare AZ31 surface, which was believed to be beneficial for avoiding the deposition of the proteins and cells on the surface and therefore improving the biocompatibility of AZ31 in blood. The interaction mechanism between this IL and AZ31 was also investigated using ATR-FTIR, which showed that both anion and cation of this IL were present in the film, and there was a chemical interaction between dpp(-) anion and the surface of AZ31 during the film formation.
镁合金是一种很有前途的可生物降解支架材料。然而，临床上可应用的商用镁基支架却很少，这是因为镁合金在体内通常会发生快速的局部腐蚀。在这项研究中，我们报道了一种基于低毒性离子液体（IL）三丁基（甲基）膦二苯基膦（P1,4,4,4 dpp）的新型镁合金 AZ31 表面涂层，以控制其腐蚀速率。重点研究了处理温度的影响。结果表明，提高处理温度可以显著改善耐腐蚀性和生物相容性。升高处理温度会在表面形成更厚（尽管仍为纳米级）且更均匀的 IL 膜。扫描电子显微镜和光学轮廓仪观察表明，裸 AZ31 在模拟体液（SBF）中浸泡 2 小时后，表面会形成许多大而深的凹坑。IL 涂层（尤其是在 100°C 下处理 1 小时）显著抑制了表面这些凹坑的形成，使腐蚀更均匀。在 100°C 下形成的 P1,4,4,4 dpp IL 膜比裸 AZ31 表面更亲水，这被认为有利于避免蛋白质和细胞在表面沉积，从而提高 AZ31 在血液中的生物相容性。ATR-FTIR 也研究了这种 IL 与 AZ31 之间的相互作用机制，结果表明，这种 IL 的阴离子和阳离子都存在于膜中，并且在成膜过程中 dpp(-)阴离子与 AZ31 表面之间存在化学相互作用。
