Bioactivity of quaternary glass prepared from bentonite clay

Abstract

Alkoxysilane precursors are the most widely used silica source for sol–gel preparation of silicate-based bioactive glass. However, due to their high cost, alternative sources such as bentonite clay are desirable. In the present work, bentonite clay was reacted with sodium hydroxide (NaOH) to extract sodium metasilicate (Na2SiO3). The obtained Na2SiO3 was converted to gel which was then sintered at 950 ℃ for 3 h to give the bioactive glass in the quaternary composition SiO2–NaO–CaO–P2O5. The resulting glass was incubated in simulated body fluid (SBF) for 0–7 days to evaluate the bioactivity. Furthermore, glass samples were characterized before and after SBF study by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Results obtained showed the presence of Na2Ca2Si3O9 (combeite) crystal as the major crystalline phase and the formation of hydroxyapatite (HA) and hydroxycarbonated apatite (HCA) on the surface of the glass after immersion in SBF. The material showed potentials for application as scaffold in bone tissue repair.