In vitro evaluation of silver doped wollastonite synthesized from natural waste for biomedical applications

The present study deals with a detailed investigation of bioactivity, degradation and antibacterial activity of silver doped wollastonite (CaSiO3) synthesized using natural waste. Natural waste such as rice husk ash (RHA) and eggshells have been used as precursors for extracting silica (SiO2) and calcium oxide (CaO) respectively. Silver oxide (AgO) (0, 2, 4 and 6 mol%) doped wollastonite at the expense of CaO were synthesized through sol-gel process, and were characterised with thermogravimetric and differential thermal analysis (TG/DTA), X-ray diffractometer (XRD), Fourier transform infrared (FTIR) spectroscopy and Scanning electron microscopy-energy dispersive spectrometer (SEM-EDS). Thermal analysis revealed that the crystallization temperature of all samples was below 800 degrees C, and so all samples were sintered at this temperature. The bioactivity was explored in vitro, employing simulated body fluid (SBF) and the hydroxyapatite phase formation was confirmed by XRD. FTIR spectra showed the presence of characteristic functional groups, while, surface morphology was observed using SEM images, revealing the spherical shape of hydroxyapatite. The chemical constituents of apatite were confirmed by EDS spectra. The degradation study results have shown that degradation rate of silver doped wollastonite decreased with increase in silver content. Antibacterial activity was tested using disk diffusion method against different bacteria. Silver doped wollastonite showed good antibacterial activity and enhanced bioactivity.