Enhancing biocompatibility and antibacterial activity of Mg/HA (magnesium-hydroxyapatite) composites with silver nanoparticles for orthopedic implant applications

Recent medical research is focusing on biodegradable and biocompatible magnesium-based alloy materials and composites for repairing damaged bone structures. Their rapid deterioration and poor antimicrobial properties prevent them from being used as implant materials. Hence, this study aims to develop novel nanocomposites (Mg/5% HA and Mg/5% HA/1% Agnp) by innovative ultrasonic-aided squeeze-rheo casting to enhance the mechanical, corrosion, and biological properties of Mg-based composites, demonstrating their potential as biodegradable implants with a low implant/tissue infection risk. Herein, the fabrication process involved the application of 2 kW power and 20 kHz acoustic waves during ultrasonic treatment of the molten magnesium alloy to achieve uniform dispersion of HA and Agnp, followed by squeeze pressure to solidify the composite materials. The morphological and phase analysis reveals minimal Agnp aggregation, surface defects, and presence of primary Mg, HA, and Ag phases without intermetallic phase formation. Furthermore, potentiodynamic polarization study reveals that Agnp-reinforced nanocomposites have lower corrosion rate (0.82 mm/y) than pure Mg (1.15 mm/y) and Mg/HA (2.55 mm/y) composites in a simulated body fluid (SBF). Likewise, the contact angle testing and MTT assay demonstrated improved cell adhesion and proliferation properties of the nanocomposite. Also, the release of Ag+ ions during degradation inhibited colony-forming units of E. coli bacteria and disrupted its cell membrane, proving its bactericidal properties. Altogether, these novel nanocomposites (Mg/5% HA/1% Agnp) may be suitable for biodegradable implants with a low implant/tissue infection risk.