Sol-gel synthesis and characterization of ternary bioactive glass with different compositions

Abstract

In this research, replacement of calcium oxide by phosphate content by different ratios (Ca/P = 37.5:2.5, 35:5, 32.5:7.5) in ternary glass system, SiO₂-CaO-P₂O₅ were synthesised by sol-gel method using tetraethyl orthosilicate (TEOS), triethyl phosphate (TEP) and calcium nitrate tetrahydrate as the precursors of SiO₂, CaO and P₂O₅ respectively. The properties of physical, structural as well as in vitro bioactivity for each composition were determined. The characteristics and properties of gel-glass were analysed using pycnometer, Archimedes test, X-Ray Fluorescence, Brunauer-Emmet-Teller, Fourier Transform Infrared Spectroscopy, X-Ray Diffraction and Scanning Electron Microscopy. The gel-glass pellets were subjected to immersion studies in simulated body fluid (SBF) for seven days. All the compositions showed good bioactive behaviour tested in SBF which confirmed that apatite-like layer had formed on the surface of the bioglass. However, for identical gel-glass with highest phosphate content (Ca:P=32.5:7.5) showed reduction in the formation of carbonated apatite. In conclusion, higher phosphate content leads to the higher formation of bridging oxygen atom, higher amorphous silicate structure and higher number of phosphate crystallites within the matrix, which affected the apatite forming ability of the gel-glass. Lower presence of phosphate content in sol-gel glass composition promotes the crystal growth of apatite.