FABRICATION OF RADIOPAQUE BIOACTIVE GLASS COATINGS WITH ENHANCED ANTIBACTERIAL ACTIVITY BY APS THERMAL SPRAY

Bioactive glass 45S5 (composition: 45SiO 2 , 24.5CaO, 24.5Na 2 O, 6P 2 O 5 wt. %) has shown significant potential in biomedical applications due to its extensive research and promising clinical outcomes. Its versatile glass structure enables the development of novel bioactive glasses by incorporating additional ions into the original composition. These modifications improve mechanical properties, an affect melting temperature, biocompatibility, bioactivity, and antibacterial activity. Metallic implants can benefit from surface functionalization with bioactive glass (BG) coatings, which combine the mechanical strength of metallic substrates with the enhanced biocompatibility and bioactivity of BG. This synergy creates an optimized system for long-term use in musculoskeletal applications, with added radiopacity and antibacterial properties tailored for biomedical needs. In this study, bismuth oxide was progressively incorporated into 45S5 BG using a melt-quench method, followed by grinding to produce fine powders (< 40 µm). Structural and compositional analysis confirmed the amorphous nature of the glass with bismuth integrated into its network. The modified BG powders exhibited enhanced radiopacity and antibacterial activity, with no observed cytotoxic effects on osteoblast cells. Bioactivity, determined by the local formation of carbonated apatite on the glass surface upon immersion in simulated body fluid, was slightly reduced. The glass composition with the best combination of radiopacity, antibacterial activity, and cell viability was used as a feedstock to fabricate coatings on Ti6Al4V substrates via atmospheric plasma spraying (APS). A design of experiments (DoE) approach optimized the coatings' mechanical properties, adhesion, porosity, and thickness. While the coatings improved the cell viability on metallic substrates, the antibacterial properties observed in the feedstock powder were not retained. To address this, the bismuth content in the feedstock powders and the coating thickness were increased to enhance the antibacterial activity of the coatings.