Mechanical Properties, Degradation Behavior, and Cytocompatibility of Zn–Mg–Graphene Nanoplatelets Composite for Orthopedic‐Implant Applications

Abstract

Zinc (Zn)‐based materials reveal inadequate mechanical properties as orthopedic biodegradable implantable materials, which limits their biomedical applications. Herein, Zn–xMg (magnesium) composites (x = 0.5, 1.0, 1.5, and 2.0 wt%) reinforced with 0.2 wt% graphene nanoplatelets (GNP) are obtained via powder metallurgy and hot‐pressing sintering. The addition of 0.5–2.0 wt% Mg into Zn–0.2 wt% GNP composite resulted in the formation of Mg2Zn11 and MgZn2 phases without any additional intermetallic carbide phases. The hot‐pressing sintered (HPS) Zn–0.5Mg–0.2GNP composite exhibits a compressive yield strength of 169 ± 18 MPa, an ultimate compressive strength of 270 ± 39 MPa, a compressive strain of 17 ± 6%, and a microhardness of 86 ± 2 HV. Electrochemical corrosion testing reveals that corrosion resistance of HPS Zn–xMg–0.2GNP composites decreases with increasing Mg content, while immersion tests in Hanks’ balanced salt solution for 30 d indicate that the degradation rate increases from 0.032 to 0.141 mm y−1 by increasing Mg content from 0 to 2.0 wt%. In vitro cytotoxicity assessments using SaOS2 human osteoblast cells show >90% viability following exposure over 5 d to 12.5% extract concentrations of all HPS composites. The HPS Zn–0.5Mg–0.2GNP composite exhibits the appropriate material properties for biodegradable bone‐implant applications.