Zinc-Magnesium alloy as a degradable bone plate

Abstract

Medical degradable bone plates faced many challenges as toxicity, degradation rate and mechanical properties. Magnesium alloys as first degradable plates have many problems. Zinc alloys also suffer from toxicity of degradation product. In this paper, Zinc-based alloys with different ratios of Mg (magnesium) were fabricated to find the best combatable degradable bone plate for medical applications. Zinc with Mg (0.5, 1.0, 1.5 and 2.0 wt. %) were prepared. In-vitro study. effect on cell viability, adhesion, cellgrowth, and degradation tests of Zinc- XMg alloys were done. Mechanical Compatibility and Microstructure of Zn-XMg were investigated using SEM (scanning electron microscope) and EDS (energy dispersive spectrometer). The results of the analyzed alloys' compositions showed that Zn-xMg were comparable. Microstructurally, all fabricated alloys had a dendritic structure of Mg + MgZn matrix. When the percentage of Mg wt.% increased to one, small elongated particles were appeared obviously at grain boundaries. The presence of Mg + MgZn mixture in the structure effects on mechanical properties. Compression strength of Zn–Mg alloy were enhanced from 65-75 MPa for pure zinc to 600 MPa and 620 for Zn–0.5 Mg alloy and Zn–2Mg alloy. High hardness and wear resistance were observed for alloy with 0.5% Mg. Tensile strength of Zn-Mg alloy were enhanced from 39 MPa for pure zinc to 320 MPa and 300 MPa for Zn-0.5 Mg alloy and Zn-2Mg alloy. For all the investigated alloys, the degradation rate values were increased with increasing amount of Mg %,. On the contrary, the results of mechanical properties showed that the highest ultimate tensile strength value was recorded when Mg wt. % was (0.5). Electrochemical measurements show degradation rates ranged from 0.038 to 0.45mm/year with no toxicity on cell. So, it has great advantage that maintain high strength for long period till restoring damaged bone. Cell viability, adhesion and cell growth were significantly high for Zn- 0.5Mg. Evidently, the fabricated Zn-0.5Mg alloy is a novel biodegradable plate for biomedical orthopedic application. Its mechanical properties improved using 0.5Mg.% which acts as areinforced material for zn plate. This component of alloy exhibit the suitable degradation rate with no toxicity, mechanical strength, surface properties that needed to encourage cells and minerals to form a new bone.