Investigating the mechanical characteristics, microstructure, biodegradation, and in vitro biocompatibility potential of HAp-assisted, nano-scale TiO2 @Al ₂ O ₃ strengthen Sr-reinforced Mg-Zn composite for internal fracture fixation

This study develops a hybrid-reinforced magnesium (Mg) composite for orthopedic implants by incorporating bioactive hydroxyapatite (HAp) and inert TiO2@Al2O3 nanoparticles. HAp is synthesized via controlled precipitation, while TiO2-coated Al2O3 was produced using a sol-gel method. A multi-phase Mg-Zn-HAp-TiO2@Al2O3-Sr composite (PMS) is compared with pure Mg (PM). The PMS composite exhibited uniform reinforcement distribution, significantly enhanced mechanical properties (178.5% increase in TYS and 107.1% increase in UTS compared to PM), and a reduced corrosion rate of 0.275 mm/year. Cytocompatibility results showed over 80% cell viability at 25% and 50% extract concentrations on day 1, 3 and 5. These findings demonstrate that synergistic reinforcement with Zn, HAp, TiO2@Al2O3, and Sr effectively improves the mechanical performance, corrosion resistance, and biocompatibility of Mg for orthopaedic implant applications.