Get access

Sol–Gel Synthesis of Bioactive Glass-Ceramic 45S5 and its in vitro Dissolution and Mineralization Behavior


Author to whom correspondence should be addressed. e-mail:


Amorphous bioactive glasses such as 45S5 have been successfully used in bone-filling therapy in non-load bearing biomedical applications for decades. In this study, we challenge the predilection to amorphous over crystalline ceramics by investigating the effect of synthesis route on surface texture, in vitro dissolution, and mineral formation on powders produced by sol–gel and glass melt-casting methods. Many reports have indicated bulk crystalline bioactive glass-ceramics to be less bioactive than their amorphous counterparts as measured by the onset time for mineral formation. Bioactive glass 45S5 was synthesized using the sol–gel method followed by heat treatment to produce a semi-crystalline structure and was compared against commercially available amorphous melt-cast 45S5 powder. Gel-derived samples were stabilized at 700°C making more than 80% of the structure crystalline. Dissolution of 45S5 glass-ceramic in powder form(particle diameter 12 μm) was studied by in vitro immersion in simulated body fluid solution for various periods of time. The immersed powders were then analyzed through X-ray diffraction (XRD), Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS), Differential scanning calorimetry (DSC), and thermogravimetric analysis (DSC/TGA), and Fourier transform infrared spectroscopy (FTIR) to determine the onset time for surface mineralization, and were compared with the melt-cast powder as a control. The rates of dissolution and onset time for mineral formation were similar for the gel-derived powder as compared with the melt-cast control; it is proposed that the higher surface area of the sol–gel powder overcame the penalty usually associated with lower dissolution rates of crystalline materials, implicating surface texture as a much more important determinant of dissolution and mineralization behavior than mere crystallinity.