Emergent Materials (2522574X)
The development of temporary biodegradable orthopedic implants has been a key focus in recent years to reduce healthcare costs, minimize the need for multiple surgical interventions, and improve patient satisfaction. In this study, biodegradable magnesium-tin (Mg-Sn) composites reinforced with biphasic calcium phosphate nanoparticles (nBCP) were synthesized and evaluated for advanced orthopedic implant applications. Initially, nBCP was synthesized from bovine tibia bone using a thermal process. Composite samples, including Mg-5wt%Sn, Mg-5wt%Sn-1.25wt%nBCP, and Mg-5wt%Sn-2.5wt%nBCP, were fabricated using the stir casting method, and some underwent homogenization heat treatment at 450 °C for 24 h, followed by hot rolling at 445 ± 10 °C. The microstructure, mechanical properties, corrosion resistance, and biocompatibility of these composites were comprehensively analyzed. Optical microscopy (OM) and field emission scanning electron microscopy (FESEM) revealed significant grain refinement in the Mg-5Sn base alloy and an increase in grain boundaries after hot rolling and the addition of nBCP. X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS) confirmed the formation of a secondary Mg2Sn phase in the composites. Tensile tests showed that the ultimate tensile strength (UTS) and yield strength of the rolled samples were approximately 1.7 times higher than those of the as-cast samples, although the elongation percentage was reduced by half. The highest UTS value, 138 MPa, was observed in the rolled Mg-5wt%Sn-2.5wt%nBCP sample. Potentiodynamic polarization and electrochemical impedance spectroscopy revealed a reduction in corrosion resistance after hot rolling, attributed to increased dislocation density and internal strain energy; however, the rolled composite containing 2.5wt%nBCP exhibited superior corrosion resistance compared to other rolled samples. Cell toxicity assays (MTT) using MG-63 cells demonstrated enhanced biocompatibility in nBCP-containing samples over a 7-day period, with the rolled Mg-5wt%Sn-2.5wt%nBCP composite showing the highest cell survival rate. Overall, the findings suggest that the rolled Mg-5wt%Sn-2.5wt%nBCP composite is a promising candidate for the development of orthopedic implants. © Qatar University and Springer Nature Switzerland AG 2025.
