Multifunctional Y2O3-Modified Borotellurite Bioactive Glasses for Bone Tissue Engineering Applications

Developing bioactive glasses that simultaneously provide mechanical reliability, cytocompatibility, controlled ion release, and antibacterial functionality remains a major challenge in bone tissue engineering. In this study, borotellurite-based bioactive glasses with the composition (45 − x)TeO2–20Na2O–10CaO–15P2O5–10B2O3–xY2O3 (x = 0–7 mol.%) were designed to elucidate the role of Y2O3 in governing composition–structure–property relationships. Structural, thermal, mechanical, ion-release, bioactivity, cytocompatibility, cell-adhesion, and antibacterial properties were systematically evaluated, and the most promising composition was further modified by silver surface coating. Y2O3 incorporation markedly enhanced thermal stability, hardness, and fracture resistance, with hardness reaching 4.317 GPa at 7 mol.%, while the highest compressive strength was achieved at 1 mol.% Y2O3 (67.97 MPa). Importantly, Y2O3 regulated dissolution behavior and mitigated the severe long-term cytotoxicity of the undoped glass, maintaining all doped compositions above the ISO 10993-5 threshold after 30 days. Higher Y2O3 contents also promoted osteoblast adhesion and facilitated bioactive surface layer formation following SBF immersion. No detectable E. coli adhesion was observed, whereas the TBY3 composition exhibited the lowest S. aureus adhesion, further improved by silver coating. These results demonstrate Y2O3 as an effective multifunctional modifier for engineering mechanically robust, biologically favorable, and antibacterial borotellurite bioactive glasses for bone repair.