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

Abstract This study develops a hybrid-reinforced magnesium (Mg) composite for orthopaedic implants by incorporating bioactive hydroxyapatite (HAp) and inert TiO 2 @Al 2 O 3 nanoparticles. HAp is synthesized via controlled precipitation, while TiO 2 -coated Al 2 O 3 is produced using a sol–gel method. A multi-phase Mg–Zn–HAp–TiO 2 @Al 2 O 3 –Sr composite (PMS) is compared with pure Mg (PM). The PMS composite exhibited uniform reinforcement distribution, significantly enhanced mechanical properties (161.29% increase in tensile yield strength and 116.66% increase in UTS compared to PM), and a reduced corrosion rate of 0.661 mm yr −1 . 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, TiO 2 @Al 2 O 3 , and Sr effectively improves the mechanical performance, corrosion resistance, and biocompatibility of Mg for orthopaedic implant applications.