In vitro bioactivity, mechanical behavior and antibacterial properties of mesoporous SiO2-CaO-Na2O-P2O5 nano bioactive glass ceramics

Abstract

Bioactive ceramics, glasses and glass ceramics have the ability to enhance the bone formation and bond to surrounding tissue. In this study, we report on the synthesis of mesoporous nanobioactive glass ceramic with the modified composition of quaternary system 50% SiO2 – 26% Na2O - 20% CaO– 4% P2O5 (Ca/P: 5) [i.e.50S20C] by sol-gel method and succeeded by heat treatment. The as-dried sample was calcined at various temperatures such as 100 °C, 300 °C, 500 °C, 700 °C and 900 °C for 24 h.The weight loss measurement was carried out using Thermogravimetric (TG) analysis. The structural features were characterized by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM) & Energy Dispersive Spectroscopy (EDS) analysis. The results revealed that the synthesized glass ceramic stabilized at higher temperature (700 °C and 900 °C)making more formation of the crystalline phase of sodium calcium silicate. The density and porosity measurements were carried out by using the Archimedes immersion method. The mechanical properties of the glass ceramic exhibit the compressive strength as69 MPa and 72 MPa for 700 °C and 900 °C, respectively. From the obtained results, we confirmed the calcined bioactive glass ceramic nanoparticles at 700 °C and 900 °C having a better crystallization, crystallite size with high surface area, high density, suitable porosity of mesoporous with dense microstructure and adequate mechanical properties. Furthermore, in vitro bioactivity character of calcined nanobioactive glass ceramics were studied by using an immersion of nanopowders into Stimulated Body Fluid (SBF) solution for two different time periods such as 7 and 14 days. After soaking the glass ceramic nanopowders in SBF, the structural and morphological changes were determined by using XRD, FTIR and FESEM & EDS analysis, respectively. The in vitro results exhibited that crystallization did not retard the samples bioactivity which indicates the increase of material bioactivity while calcining temperature was increased and it is used to fabricate tissue engineering scaffolds with sustained mechanical properties. Moreover, the enhanced bactericidal behavior of glass ceramic has also been studied. An antibacterial study revealed that the prepared bioactive glass ceramic show a significant effect on two bacteria E. coli and S. aureus.