Effects of Ga/Ag addition on corrosion behavior, cytotoxicity, and antibacterial activity of biodegradable Mg-2Zn alloy

Ga and Ag elements with good biocompatibility are introduced into a Mg-2Zn alloy to design an antibacterial alloy able to inhibit the bacterial infection of bone implants. The effects of Ga/Ag element on the corrosion behavior, cytotoxicity, and antibacterial activity of the as-extruded Mg-2Zn alloy are investigated in vitro. The immersion measurement results show that the mass loss rate of the Mg-2Zn alloy increases from 0.09 +/- 0.006 mm/y to 0.24 +/- 0.03 mm/y after the addition of 0.5 wt% Ga and 0.5 wt% Ag. This is due to that Ga and Ag elements can increase the cathodic current density and reduce the charge transfer resistance (Rct). Furthermore, Ag is enriched in the Mg7(ZnAg)3 phase, resulting in an increase in the micro-galvanic corrosion and the maximum local corrosion depth. The cytotoxicity tests reveal that Ag and Ga do not induce toxicity to osteoblastic cells (MC3T3-E1) after incubation for 72 h. Moreover, the addition of Ag and Ga increases prominently the antibacterial activity of Mg-2Zn alloys, which is principally associated with the release of Ga and Ag ions and the alkaline antibacterial environment.