Zinc/Potassium-Doped Bioactive Glass With Enhanced Antimicrobial Activity Against Gram-Negative Bacteria

Bioactive glasses (BGs) are widely investigated for biomedical applications due to their bioactivity, ion release capability, and potential antimicrobial behavior. In this work, a novel zinc/potassium-doped BG, designated as Gaia-GN, was synthesized using the melt-quench technique. The thermal behavior was characterized through differential thermal analysis (DTA), thermogravimetry (TG), and heating microscopy (HM), which revealed a glass transition temperature of 513°C and a broad processing window suitable for viscous-flow sintering. Subsequently, Gaia-GN powders were thermally processed to obtain sintered specimens. XRD analysis showed that sintering at relatively low temperatures, namely 600°C, produced a compact and predominantly amorphous structure, minimizing the formation of crystalline phases. In addition, mechanical properties were evaluated by Vickers micro-indentation, determining Vickers hardness, Young's modulus, and fracture toughness using four different theoretical models. The results suggest that the combined presence of Zn and K improves thermal stability and mechanical performance compared with conventional formulations such as 45S5 Bioglass and S53P4. Finally, antimicrobial assays were conducted, revealing a strong antimicrobial action of the glass against Gram-negative bacteria. Overall, these findings underscore the potential of the new K/Zn-doped BG not only for its antibacterial properties but also for applications requiring thermal processing, such as the fabrication of scaffolds or coatings on metallic substrates.