Effect of boron oxide addition on structural, thermal, in vitro bioactivity and antibacterial properties of bioactive glasses in the base S53P4 composition

Abstract

The present work explores the potential of B2O3 substituted bioactive glasses towards improvement in surface apatite formation along with better cell proliferation and improved antibacterial properties. While the base glass was selected from SiO2-Na2O-CaO-P2O5 system (commercially available S53P4 glass), four B2O3 modified glass compositions were formulated by replacing SiO2 in the base glass composition by B2O3 with 25, 50, 75 and 100%. To understand the amorphous nature of the glasses as well as the structural changes in the glasses, X-ray diffraction (XRD) analysis and Fourier transform infrared (FTIR) spectroscopy were performed, respectively. The thermal behaviour of the glasses were analysed using differential scanning calorimetry (DSC) and an improvement in the glass stability factor (∆T), was observed at optimized B2O3 concentration. The apatite formation on the surfaces of glasses after bioactivity study for various time periods was analysed using XRD and FTIR. A gradual increase in the pH value and ion concentration (e.g. Ca2+, B3+) in simulated body fluid (SBF) was observed along with faster apatite formation with gradual increase in B2O3 substitution. The in vitro cell proliferation studies using MTT assay demonstrate that the cell proliferation was better on the glasses (BG1B, BG2B and BG3B) compared to base glass (BG0B). Antibacterial study was performed using broth microdilution method against Escherichia coli (E. coli) bacteria exploring the antibacterial effects of these glasses from which B2O3 substituted glasses were observed to exhibit improved antibacterial properties compared to base glass (BG0B).