Fabrication and Properties of Zn-Containing Intermetallic Compounds as Sacrificial Anodes of Zn-Based Implants

TL;DR

Researchers created zinc-containing compounds that could help control the degradation of zinc-based medical implants by acting as sacrificial anodes.

Contribution

The study introduces new Zn-containing intermetallic compounds as sacrificial anodes to improve the performance of Zn-based implants.

Findings

MgZn2, CaZn13, and Ca2Mg6Zn3 compounds showed more negative corrosion potentials than pure Zn, making them suitable sacrificial anodes.

The compounds degraded proportionally to their elemental composition and promoted calcium-phosphate deposition in simulated body fluid.

The compounds exhibited good cytocompatibility, with 10% extracts supporting high cell activity on MC3T3-E1 cells.

Abstract

In the field of degradable metals, Zn-based implants have gradually gained more attention. However, the relatively slow degradation rate compared with the healing rate of the damaged bone tissue, along with the excessive Zn2+ release during the degradation process, limit the application of Zn-based implants. The use of intermetallic compounds with more negative electrode potentials as sacrificial anodes of Zn-based implants is likely to be a feasible approach to resolve this contradiction. In this work, three intermetallic compounds, MgZn2, CaZn13, and Ca2Mg6Zn3, were prepared. The phase structures, microstructures, and relevant properties, such as thermal stability, in vitro degradation properties, and cytotoxicity of the compounds, were investigated. The XRD patterns indicate that the MgZn2 and CaZn13 specimens contain single-phase MgZn2 and CaZn13, respectively, while the Ca2Mg6Zn3 specimen contains Mg2Ca and Ca2Mg6Zn3 phases. After purifying treatment in 0.9% NaCl solution, high purity Ca2Mg6Zn3 phase was obtained. Thermal stability tests suggest that the MgZn2 and CaZn13 specimens possess good thermal stability below 773 K. However, the Ca2Mg6Zn3 specimen melted at around 739.1 K. Polarization curve tests show that the corrosion potentials of MgZn2, CaZn13, and Ca2Mg6Zn3 in simulated body fluid (SBF) were −1.063 VSCE, −1.289 VSCE, and −1.432 VSCE, which were all more negative than that of the pure Zn specimen (−1.003 VSCE). Clearly, these compounds can act as sacrificial anodes in Zn-based implants. The immersion tests indicate that these compounds were degraded according to the atomic ratio of the elements in each compound. Besides that, the compounds can efficiently induce Ca-P deposition in SBF. Cytotoxicity tests demonstrate that the 10% extracts prepared from these compounds exhibit good cell activity on MC3T3-E1 cells.

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