Abstract
Bone implants are expected to possess antibacterial ability and favorable biodegradability. Ag possesses broad-spectrum antibacterial effects through destroying the respiration and substance transport of bacteria. In this study, Ag was introduced into Mg-3Zn-0.5Zr (ZK30) via selective laser melting technology. Results showed that ZK30-Ag exhibited a strong and stable antibacterial activity against the bacterium Escherichia coli. Moreover, the degradation resistance was enhanced due to the comprehensive effect of positive shifted corrosion potential (from -1.64 to -1.53 V) and grains refinement. The positive shifted corrosion potential reduced the severe galvanic corrosion by lowering the corrosion potential difference between the matrix and the second phase. Meanwhile, the introduction of Ag caused the grain refinement strengthening and precipitated-phase strengthening, resulting in improved compressive yield strength and hardness. Furthermore, ZK30-0.5Ag exhibited good biocompatibility. It was suggested that Ag-modified ZK30 was potential candidate for bone implants.
Highlights
Magnesium (Mg) alloy has attracted increasing attention as potential bone implant due to its favorable biocompatibility, proper mechanical properties, and inherent biodegradability [1, 2]
The results showed that the antibacterial ability of ZK30-0.5Ag was significantly higher than that of ZK30 in neutral environment, confirming that Ag played key roles in its improved antibacterial property
ZK30-xAg exhibited good antibacterial activity, revealing that Ag played a key role in the improvement of antibacterial property by destroying bacterial respiratory and material transportation
Summary
Magnesium (Mg) alloy has attracted increasing attention as potential bone implant due to its favorable biocompatibility, proper mechanical properties, and inherent biodegradability [1, 2]. Chen et al prepared the Ti-Ag alloys by powder metallurgy method and found that the alloys possessed good antibacterial effect against staphylococcus aureus when the Ag+ concentration was about 0.05 mg/L [16]. The degradation rate of Mg alloys in human body is too fast, because the corrosion potential of magnesium is very low (-2.364 V) [17]. Selective laser melting with a rapid solidification effectively reduces the grains size and composition segregation, both of which contribute to the enhancement of corrosion resistance of Mg alloys [19].
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