Tantalum Doped Bioactive Glass: Towards a Pro-Regenerative and Antibacterial Response ^†

The use of synthetic implants for bone restoration is associated with the risk of bacterial colonization, resulting in implant failure. Bioactive glasses (BG) are among the most used materials in bone regeneration applications. However, this material does not have an effective antibacterial activity capable of maintaining an infection-free wound for long. A material that could respond to this need is tantalum (Ta), as it is biocompatible, has antibacterial properties, promotes osseointegration, and has hemostatic capacity. This work aims to improve the performance of BG-coated implants by doping BG with metal ions known for their excellent anti-microbiological activity. To achieve this goal, 45S5 Bioglass™ was doped with Ta, prepared using the melt quenching technique, and then characterized both physically and biologically. The biological analysis focuses on cell responses and microbiological assays. Cell responses were analyzed by cytotoxicity assays, using both osteoblasts and macrophages, and macrophage polarization. The microbiological assays allow minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) determination. The incorporation of Ta ions does not show a significant change in the glass structure at low concentrations; however, for the highest Ta concentration, Ta-doped BG presented characteristic peaks of the Ta2O5 crystal. Furthermore, an increase of Ta in BG led to an increase in cell viability for both types of cells tested (Saos2 and THP-1). In what concerns the anti-bacterial activity, the effect of incorporating 4 mol% Ta in BG led to an effective bactericidal activity against both Gram-negative (Escherichia coli) and Gram-positive bacteria (methicillin-resistant Staphylococcus aureus). These results show that Ta-doped BG is a promising material for accelerating tissue regeneration and preventing bacterial infections.