Enhanced Mechanical Properties, Corrosion Resistance, Cytocompatibility, Osteogenesis, and Antibacterial Performance of Biodegradable Mg-2Zn-0.5Ca-0.5Sr/Zr Alloys for Bone-Implant Application.

Magnesium (Mg) alloys have been widely used in bone fixation, bone repair, and cardiovascular stents as biodegradable bone-implant materials. However, their clinical application is limited due to their fast corrosion rate and poor mechanical stability. Here we report the development of Mg-2Zn-0.5Ca-0.5Sr (MZCS) and Mg-2Zn-0.5Ca-0.5Zr (MZCZ) alloys with improved mechanical properties, corrosion resistance, cytocompatibility, osteogenesis performance, and antibacterial capability for biodegradable bone-implant applications. The hot-extruded (HE) MZCZ sample exhibited the highest ultimate tensile strength of 255.8±2.4 MPa and the highest yield strength of 208.4±2.8 MPa among all alloy samples and an elongation of 15.7±0.5% due to the recrystallization and grain-refining effect of Zr. The HE MZCS sample showed the highest corrosion resistance among all samples, with the lowest corrosion current density of 0.2±0.1 μA/cm 2 and lowest corrosion rate of 4±2 μm/y obtained from electrochemical testing, and a degradation rate of 368 μm/y and hydrogen (H 2 ) evolution rate of 0.83±0.03 mL/cm 2 /d obtained from immersion testing for 21 d in Hanks' solution. The MZCZ sample showed the highest cell viability in relation to MC3T3-E1 cells among all alloy extracts, indicating good cytocompatibility except at 25% concentration. Furthermore, the MZCZ alloy showed good antibacterial capability against S. aureus. This article is protected by copyright. All rights reserved.