Bioactive glasses co-doped with zinc and magnesium: Bioactivity, ion release, and antimicrobial activity against Gram-positive and Gram-negative bacteria

Bioactive glasses (BGs) are widely studied for their ability to bond with tissues, release biologically active ions, and exhibit antimicrobial activity. In this study, a series of Zn- and Mg-containing BGs were synthesized via the melt-quench method, varying the relative contents of ZnO and MgO. Structural and thermal properties were characterized using X-ray diffraction, differential thermal analysis, and heating microscopy, while their in vitro bioactivity was preliminarily assessed through immersion in Simulated Body Fluid. Ion release was quantified by Inductively Coupled Plasma Mass Spectrometry with Triple Quadrupole, and antimicrobial activity was tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) . The results demonstrate that compositional variations influence the physicochemical behavior, ion-release characteristics, in vitro bioactivity, and antibacterial performance of BGs. In particular, Zn content played a key role: glasses in which Zn acted mainly as a network modifier showed enhanced reactivity, sustained Zn2+ release, and strong alkalinization of the medium, which correlated with improved antibacterial activity. Notably, one of the developed formulations (Roma2) exhibited a highly favorable combination of structural stability, ion-release behavior, in vitro bioactivity, and antibacterial efficacy against both Gram-negative and Gram-positive bacteria. Overall, these findings highlight the potential of Zn- and Mg-doped BGs as multifunctional biomaterials for bone-related applications requiring antibacterial functionality.