Advanced optimization of dopant profiles in bismuth-enhanced bioactive glass through response surface methodology

The composition of constituent elements in bioactive glasses is critical for achieving properties suitable for biological applications. Even minor compositional variations can significantly alter the system's response. This study investigated silica-based bioactive glasses doped with 2, 4, and 6 wt% bismuth (Bi), utilizing an Analysis of Variance (ANOVA) model with a Central Composite Design (CCD) to examine the influence of compositional changes on structure and properties. Physical properties were characterized using Zeta potential measurements for stability, Scanning Electron Microscopy (SEM) for nanoparticle size, and Brunauer-Emmett-Teller (BET) analysis for porosity. Post-Simulated Body Fluid (SBF) investigations included transmission electron microscopy (TEM) with Selected Area Electron Diffraction (SAED) to observe hydroxyapatite (HA) formation, Energy-Dispersive X-ray (EDX) spectroscopy for compositional analysis, Fourier Transform Infrared (FTIR) spectroscopy to evaluate nanoparticle functional characteristics, and X-ray Photoelectron Spectroscopy (XPS) to determine the oxidation state of Bi. A correlation between physical properties and constituent composition was established through ANOVA. The predicted and actual values were consistent with the selected optimization model. In vitro assays confirmed the bioactivity of the synthesized samples, which were found to be biocompatible and non-cytotoxic for the intended applications.