Evaluation of biodegradable Zn-1%Mg and Zn-1%Mg-0.5%Ca alloys for biomedical applications

Abstract

Increasing interest in biodegradable metals (Mg, Fe, and Zn) as structural materials for orthopedic and cardiovascular applications mainly relates to their promising biocompatibility, mechanical properties and ability to self-remove. However, Mg alloys suffer from excessive corrosion rates associated with premature loss of mechanical integrity and gas embolism risks. Fe based alloys produce voluminous corrosion products that have a detrimental effect on neighboring cells and extracellular matrix. In contrast, Zn does not appear to exhibit a harmful mode of corrosion. Unfortunately, pure zinc possesses insufficient mechanical strength for biomedical structural applications. The present study aimed at examining the potential of two new zinc based alloys, Zn-1%Mg and Zn-1%Mg-0.5%Ca to serve as structural materials for biodegradable implants. This examination was carried out under in vitro conditions, including immersion testing, potentiodynamic polarization analysis, electrochemical impedance spectroscopy (EIS), and stress corrosion cracking (SCC) assessments in terms of slow strain rate testing (SSRT). In order to assess the cytotoxicity of the tested alloys, cell viability was evaluated indirectly using Saos-2 cells. The results demonstrate that both zinc alloys can be considered as potential candidates for biodegradable implants, with a relative advantage to the Zn-1%Mg alloy in terms of its corrosion resistance and SCC performance.

Recent research and progress of biodegradable zinc alloys and composites for biomedical applications: Biomechanical and biocorrosion perspectives

“…Squeeze casting is the most common processing technique to fabricate Zn alloys. In this process, molten metal is forced into the mold cavity under elevated pressure [ 107 , 108 ]. Gravity casting involves the direct pouring of liquefied metals from the crucible into the mold [ 109 ].…”

Updates on the research and development of absorbable metals for biomedical applications

“…This has facilitated their clinical translation (Agrawal et al 2016 ; Zhao et al 2017b ). The third base metal, i.e., zinc, has been lately added as a new family of absorbable metals (Liu et al 2016b ; Wang et al 2016a ; Levy et al 2017 ). The cytocompatibility of zinc-based metals was studied in view of its applications for bone and vascular implants (Murni et al 2015 ; Shearier et al 2016 ; Guillory et al 2016 ).…”

Designing Better Cardiovascular Stent Materials: A Learning Curve

“…It is essential for human development, but its mechanical properties are below the minimum benchmark for a stent; however, Zn alone suffers from unacceptably low TS (120 MPa), [ 2 ] so alloying has been a common practice to increase its mechanical properties. Several papers have reported on Zn‐Mg, [ 73,74 ] Zn‐Al, [ 74 ] Zn‐Ag, [ 75 ] Zn‐Mg‐Ca, [ 73 ] Zn‐Li, [ 76,77 ] Zn‐1 X ( X = Mg, Ca, Sr), [ 78 ] and Zn‐Cu [ 79 ] alloys, but only few have surpassed the minimum benchmarks for mechanical stent acceptance. A comprehensive investigation was performed on binary Zn alloys with Ca, Mg, Mn, Cu, Fe, Sr, Ag, and Li, where results showed Li and Mg exhibited the highest strengthening effects.…”