Structure, Porosity, and High-Temperature Analysis of Zinc, Copper and Cobalt Doped Sol-Gel Bioactive Glass-Ceramics for Tissue Regeneration

Understanding how the structure of bioactive glass-ceramics can change when exposed to higher temperatures during fabrication techniques, like 3D printing, is essential for accurate function in areas of tissue regeneration. A series of 45SiO₂-14.5NaO₂-14.5CaO-6P₂O₅ wt% sol-gel bioactive glass-ceramics were doped with 10 wt% zinc (Zn), 6–9 wt% copper (Cu), and 1–4 wt% cobalt (Co) during synthesis, and the overall structure was explored at room temperature (RT) and temperatures up to 600 °C. RT studies showed increased surface area (SA) and porosity in the doped glass-ceramics compared to the Control, and these properties were found to decrease significantly when heat treated to 600 °C in all samples. X-ray photoelectron spectroscopy (XPS) determined a 2 + oxidation state for all doped ions and a higher bridging oxygen:non-bridging oxygen (BO:NBO) ratio in the Control, which increased as the concentration of Cu increased in the doped glass-ceramics. At RT, two crystalline phases were found using X-ray diffraction (XRD), but as the temperature was increased, changes in crystal structure were observed. Spectroscopic studies analyzed the chemical bonds and network connectivity present in the glass-ceramics and showed a correlation between bond formation and temperature. The doped bioactive glass-ceramics present properties that could aid in tissue regeneration, but at processing temperatures above 200 °C, changes in the structure could significantly influence the materials biocompatibility.