Antibacterial Activity and Mechanisms of Magnesium-Doped Baghdadite Bioceramics for Orthopedic Implants

Baghdadite (BAG, Ca₃ZrSi₂O₉), a calcium silicate compound with zirconium incorporation, shows significant potential in medical implants. However, its susceptibility to infections poses a considerable challenge. To tackle this problem, doping biocompatible magnesium (Mg) into BAG to create Mg-BAG enhances antibacterial activity and prevents infection in orthopedic implants. Mg-BAG demonstrates effectiveness against Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa. This study finds that the antibacterial activity of Mg-BAG is multifaced including causing the generation of reactive oxygen species (ROS) within cells and disrupting membrane potential, resulting in leakage of intracellular contents. The synchrotron macro attenuated total reflectance Fourier-transform infrared microspectroscopy shows the impact of Mg-BAG on bacteria, resulting in modifications to biomolecules such as lipids, protein structures, and the stability of nucleic acids. The combined effect of Mg ions (Mg²⁺) and intracellular ROS formation contributes to the disruption of biomolecules and bacterial cell death. Mg-BAG is a promising next-generation bioceramic offering innovative nonantibiotic solutions for preventing infection.