Impact of B2O3 addition on the structural, mechanical, and biological properties of SiO2-Na2O-CaO-MgO-P2O5 -based bioactive glasses

This study comprehensively investigates the structural, optical, mechanical, and biological properties of bioactive glasses developed by incorporating B2O3 into the SiO2 -NaO-CaO-MgO-P2O5 system, aiming to enhance their performance for biomedical applications. The primary objective is to determine the effects of varying B2O3 concentrations on the mechanical strength, optical properties, and biocompatibility of these glasses, thereby highlighting their potential for critical applications such as bone tissue regeneration and biomedical implants. In this study, glasses containing 0, 5, 10, 15, 20, and 25 mol% B2O3 were synthesized using the melt-quenching method and subsequently subjected to comprehensive analyses. Structural properties were evaluated using XRD and FT-IR, optical properties were investigated via UV-Vis spectroscopy, and mechanical properties were determined through microhardness and fracture toughness tests. Additionally, in vitro biological tests were conducted using the NIH/3T3 fibroblast cell line to assess the biocompatibility of the glasses. The structural analysis results confirmed that all the glasses exhibited an amorphous structure, with increasing B2O3 content strengthening the Si-O-Si network and enhancing the structural density of the glasses. Density measurements showed that the addition of B2O3 increased the glass density from 2.27 g/cm3 (FB0) to 2.46 g/cm3 (FB25), indicating a more compact glass network. Optical analyses revealed that B2O3 reduced the optical bandgap from 3.97 eV to 3.57 eV while increasing the refractive index from 2.175 to 2.259. In terms of mechanical properties, the hardness increased from 4.122 GPa for the base glass (FB0) to 4.845 GPa for the glass with 25 mol% B2O3 (FB25). Fracture toughness peaked at 1.197 MPa·m0.5 and 1.077 MPa·m0.5for FB10 and FB15, respectively, but showed a decreasing trend for higher B2O3 concentrations. Biological tests demonstrated that the addition of B2O3 reduced cytotoxicity and improved biocompatibility. Cell viability increased from 60.6% for the base glass (FB0) to 69.7% for the glass with 25 mol% B2O3 (FB25), while cell adhesion improved significantly from 4.26% (FB0) to 27.66% (FB20). SEM analyses revealed better cell interaction and enhanced filopodia formation on the surfaces of glasses with higher B2O3 content. In conclusion, this study showed that B2O3 significantly improved the mechanical, optical, and biological properties of bioactive glasses, making them strong candidates for biomedical applications. The findings suggest that these materials hold great promise for applications such as bone tissue regeneration and biomedical implants, owing to their enhanced biocompatibility and mechanical performance.