Double-ion doped mesoporous glasses: Studies on stability, antibacterial and antioxidant properties, and bioactivity

Mesoporous bioactive glasses and especially those doped with Ce have shown significant promise as implant materials due to their antioxidant and tissue regeneration properties. In this study, cerium-doped mesoporous bioactive glasses were modified with additional therapeutic inorganic ions such as Cu, Ag, and Zn, up to a maximum of 5.3 mol% of total dopant ion, to explore their effects on stability, antibacterial and antioxidant properties and bioactivity. First, to verify the maintenance of their structural characteristics, the double-ion doped glasses were characterized by X-Ray Powder Diffraction, Scanning Electron Microscopy, and Specific Surface Area analyses. Bioactivity was tested in a simulated body fluid to assess the formation of hydroxyapatite. The antibacterial activities against Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, and Staphylococcus aureus were also evaluated. Antioxidant activities were evaluated through catalase-like and superoxide dismutase-like assays. The doping with Cu and Ag was more promising than Zn: Cu and Ag doping retain high bioactivity, whereas Zn doping inhibits it. Both Cu and Ag generated inhibition halos during antibacterial testing, with Cu exhibiting a higher antibacterial effect compared to Ag. Polyphenols, extracted from chestnut flour, were successfully loaded into the most promising (Ce/Cu, Ce/Ag) double-ion doped glasses, enhancing their antioxidant properties. All these findings suggest that double-ion doped samples, particularly those with Ce/Cu and Ce/Ag, are hopeful candidates for tissue regeneration and drug delivery systems.