The impact of Nb2O5 on in-vitro bioactivity and antibacterial activity of CaF2-CaO-B2O3-P2O5-SrO glass system

This work consists of in vitro bioactivity (in SBF) and antibacterial studies (against S. aureus and E. coli bacteria) of Nb2O5 doped bioactive glasses. X-ray diffraction and scanning electron microscopy investigations indicated deposition of Nb-HAp (hydroxyapatite) crystalline layer on the samples after exposing to SBF. The spectroscopy investigations also indicated the deposition of HAp layer on these samples. The magnitude of HAp deposited on the glasses found to be relying on concentration of Nb2O5 dopant; this conclusion was drawn by determining weight loss of the glasses due to exposure to SBF and also by assessing the variation of pH of the remnant fluid as functions of Nb2O5 content. The studies further indicated the maximal content of hydroxyapatite was deposited on the surface the glasses doped with 4.0 mol% of Nb2O5. The antibacterial studies (against E. coli and S. aureus bacteria) of these glasses indicated the maximal killing effect of bacteria of the samples admixed with 4.0 mol% of Nb2O5. This result is attributed to the occupancy of maximal fraction of Nb ions in NbO6 structural units (confirmed by IR and Raman spectroscopic results) in this sample that paved the way for easy disintegration of the glass and to act on the bacteria. Overall, the results of bioactivity studies of Nb2O5 doped bioglasses indicated that the Nb 2 0 5 not only enhanced bioactivity potential but also exhibited antimicrobial activity.