Ultrafine‐grained Zn‐0.45Li alloy with enhanced mechanical property, degradation behavior and cytocompatibility prepared by hot extrusion and multi‐pass drawing

Abstract

Biodegradable Zn-0.45Li alloys with high strength and ductility were successfully fabricated by hot extrusion and multi-pass drawing to obtain ultrafine-grained microstructures with a secondary phase of fine LiZn 4 participates. The mechanical properties, degradation behavior and cytocompatibility of the alloys were subsequently investigated. Results showed that grain refinement could be achieved in the alloys after hot extrusion and multi-pass drawing. The yield strength, ultimate tensile strength, and elongation to failure of the ultrafine-grained Zn-0.45Li alloys reached 416 MPa, 567 MPa and 55.4 %, respectively. Enhancements in both strength and elongation could be attributed to interactions between LiZn 4 and matrix dislocations, the pinning effect of LiZn 4 on grain boundaries, and grain refinement. Immersion tests and MTT cytotoxicity assay indicated that the Zn-0.45Li alloys have a corrosion rate and cytocompatibility similar to the values reported for biomedical implants.

Cytotoxicity of Biodegradable Zinc and Its Alloys: A Systematic Review

“…Nevertheless, the opposite was true for as-extruded Zn-1.2Mg alloy, which had lower cell survival than its as-cast alloys due to a higher concentration of Zn ions resulting from a higher corrosion rate [27]. This might be related to the Mg 2 Zn 11 phase, which is distributed relatively uniformly at grain boundaries and in the Zn matrix, involved in the formation of micro-galvanic cells [64,103]. Moreover, the corrosion resistance of the Zn matrix could be dramatically improved by appropriate heat treatment and plastic processing, resulting in a decrease in released metal ions and higher cytocompatibility [37,48].…”

“…All studies classified as not reliable failed to meet all of the essential criteria marked in red in the assessment tool. [38,61,64], with Zn-Mg and Zn-Cu being the predominant types. A small portion of Zn alloys comprised additional Al [47], Fe [49,50,84,85], Ca [58,77,88], Ge [55], Ti [54,87], Sr [65,72,76], Si [84], Zr [31,33], Sn [47], and V [59].…”

“…In a few studies, cell viability was determined on the basis of a fluorometric resazurin reduction method, such as CyQUANT [46] and resazurin assays [15,33]. The assays for qualitative analyses are summarized in Figure 3e, in which live/dead staining FDA/EB dye [16,44,59], Calcein-AM/PI dye [30,82,101], and FITC-phalloidin/DAPI dye [25,51,58,64,65] were the primary assays to realize the visualization of cells. Six studies did not indicate the specific assays used in qualitative assessment.…”