Properties, Bioactivity and Viability of the New Generation of Oxyfluoronitride Bioglasses.

In this study, the deposition of apatite on the surface of the glasses with a composition of 22.25Na₂O--13.5CaO--2.5P₂O₅--6.75CaF₂--(55-3x) SiO₂--xSi₃N₄ (x is the no. of moles of Si₃N₄) (where x = 0-4), was studied to examine the influence of nitrogen content on their properties, bioactivity and viability. It was established that density, glass transition temperatures, Young's modulus of elasticity, Vicker's microhardness and fracture toughness increased significantly with increasing nitrogen concentration. Bioactivity was investigated by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Hydroxyapatite (HCA) layer thickness was determined using a scanning electron microscope coupled with Energy Dispersive Spectroscopy (SEM-EDS). The bioactivity of the glasses was evaluated by dipping them in a simulated body fluid (SBF) and demonstrated that all glasses are bioactive. Cytotoxicity tests using different concentrations of bioglass powders in a cell growth environment further demonstrated that they were not cytotoxic. The biofilm formation by two bacteria's E. coli and S. marcescens was characterized by the absorbance of crystal violet. The influence on the presence of bacteria in the form of biofilms appears to be affected by the combination of two main factors: glass reactivity and nitrogen content. Additionally, the type or characteristics of the bacteria also play a significant role in this context. [ABSTRACT FROM AUTHOR]