Recent studies have indicated a great demand to optimize the biocompatibility properties of pure Zn as an implant material. For this purpose, CaZn₂(PO₄)₂·2H₂O (CaZnP) was prepared using hydrothermal treatment (HT) combined with micro-arc oxidation (MAO) on pure Zn substrate to generate biodegradable implants. The polarization test and electrochemical impedance spectroscopy indicated that the MAO1−HT coating could modulate the corrosion behavior of MAO1 by filling the crevice between the coating and the substrate. Immersion test evaluation revealed that the osteogenic properties of MAO1−HT coating were better than that of pure Zn substrate, as evidenced by the molar ratio of Ca and P, which increased after soaking in simulated body fluid (SBF) for up to 10 days. In addition, L-929 cells cultured in the 100%, 50%, and 25% extracts of MAO1−HT coated samples exhibited excellent cytocompatibility. Meanwhile, cell adhesion was promoted on the surface with high roughness generated during MAO and HT processes. In summary, the calcified coatings improved biocompatibility and adjusted the degradation rates of pure Zn, broadening the application of Zn alloys.

The effect of magnesium (Mg) content on the microstructure, mechanical properties, and cytocompatibility of degradable Zn-0.5Mn-xMg (x = 0.05 wt%, 0.2 wt%, 0.5 wt%) alloys was investigated. The microstructure, corrosion products, mechanical properties, and corrosion properties of the three alloys were then thoroughly characterized by scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD), and other methods. According to the findings, the grain size of matrix was refined by the addition of Mg, while the size and quantity of Mg₂Zn₁₁ phase was increased. The Mg content could significantly improve the ultimate tensile strength (UTS) of the alloy. Compared with the Zn-0.5Mn alloy, the UTS of Zn-0.5Mn-xMg alloy was increased significantly. Zn-0.5Mn-0.5Mg exhibited the highest UTS (369.6 MPa). The strength of the alloy was influenced by the average grain size, the solid solubility of Mg, and the quantity of Mg₂Zn₁₁ phase. The increase in the quantity and size of Mg₂Zn₁₁ phase was the main reason for the transition from ductile fracture to cleavage fracture. Moreover, Zn-0.5Mn-0.2Mg alloy showed the best cytocompatibility to L-929 cells.

Zinc (Zn) alloys are being developed as the degradable biomaterial. However, the corrosion mechanism of Zn in the gastrointestinal environment is seldom investigated and needs to be addressed. In this study, the impacts of enzymes on the degradation of pure Zn via electrochemical measurements and immersion were investigated. Pepsin and pancreatin affected the degradation of pure Zn. In contrast with the solutions without enzymes, the degradation rates declined with the addition of enzymes in solutions. However, localized corrosion was observed because the adsorption of pepsin was not a perfect barrier to prevent corrosion. The adsorbed pancreatin protected the samples from corrosion mainly at the initial stage of immersion. With immersion in the simulated intestinal fluid, adsorption and desorption of pancreatin occurred simultaneously on the sample surface. These findings allow the development of Zn alloy-implanted devices for the digestive tract as well as the understanding of the Zn corrosion mechanism in the gastrointestinal environment.