Metallurgical Gallium Additions to Titanium Alloys Demonstrate a Strong Time-Increasing Antibacterial Activity without any Cellular Toxicity

Orthopedic metallic devices are often related with devasting complications due to acute prosthetic joint infections. Gallium (Ga) antibacterial activity has been demonstrated by the evidence that Ga in solution ionizes in a Ga³⁺ trivalent form that replace Fe³⁺ thus arresting metabolism. However, it is not clear whether such effect is restricted only to Ga³⁺ release laps. Accordingly, here we investigated Ga addition into titanium alloys using metallurgical methods, thus realizing intermetallides of a very high stability that contain Ga in the range of 1, 2, 20, and 23% wt. ICP-OES analysis confirmed that Ga ions were not released from the specimens regardless of the Ga amount. These alloys ensured long-lasting Ga effect toward multidrug resistant Staphylococcus aureus, whose metabolic activity was reduced of >80% in comparison with controls. Finally, specimens cytocompatibility was confirmed by direct and indirect contact evaluations with mature osteoblasts and preosteoblasts progenitor cells.