Fabrication and properties of porous Zn-Ag alloy scaffolds as biodegradable materials

Porous Zn-xAg binary alloy scaffolds (where x = 1.0 and 3.5 wt.%) with porosity of 59.1 ± 0.7% were successfully prepared as biodegradable biomedical implant materials using air pressure infiltration method (APIM) in this work. NaCl particles of around 100-400 μm in size were used as space holders. Their morphologies and structures, compressive mechanical properties, corrosion characterizations in simulated body fluid (SBF), and antibacterial ability were studied in detail. Scanning electron microscopy imaging shows that the grain sizes of porous Zn scaffolds are refined to some extent due to the addition of Ag element. The compressive plateau stresses at 3% strain for the porous Zn-3.5Ag, Zn-1Ag and Zn scaffolds with a porosity of 59.1 ± 0.7% are around 13.7 ± 0.2 MPa, 5.5 ± 0.2 MPa and 4.0 ± 0.3 MPa, respectively. The mean weight loss rate of porous Zn-Ag alloy scaffolds is about 1.1 mg/day during immersion tests, which is much less than the tolerable limit of Zn intake (40 mg/day). XRD results suggest that the corrosion products on the degraded surface consisted mainly of ZnO, Ca3(PO4)2 and Zn(OH)2. Antibacterial tests indicate that the antibacterial ability of the porous Zn-Ag scaffolds becomes higher and higher with the increase of Ag content.