In vitro bioactivity and degradation behaviour of β-wollastonite derived from natural waste.

Calcium silicate ceramics, in particular wollastonite (CaSiO3), is the most commonly used bioactive material for bone regeneration and repairing applications. The present study aims to synthesize cost effective wollastonite using natural waste materials such as rice husk ash (RHA) and eggshells, sources of silica and calcium oxide respectively. Wollastonite was prepared by sol-gel method and based on thermogravimetric and differential thermal analysis (TG/DTA) results the samples were sintered at 850 °C. X-ray diffractometer (XRD) revealed that the sintered samples possess single phasic β-wollastonite. The assessment of bioactivity was examined using in vitro studies by immersing the pellets in simulated body fluid (SBF) for different time periods (3, 7, 14, 21 days). The growth of hydroxyapatite layer on the surface of the sample was analysed using XRD, Fourier transform infrared (FTIR) spectroscopy and Scanning electron microscopy-energy dispersive spectrometer (SEM-EDS). The significant change in pH of the SBF solution was observed during the first 11 days of immersion, after which the pH was saturated. Biodegradation test was performed in SBF and Tris buffer solutions according to ISO 10993-14 standard, and the test revealed that the ceramic pellets showed lower degradation rates with slow dissolution of ionic species. MTT assay demonstrated that the prepared wollastonite exhibits cytocompatibility with MG-63 cells at different dosage (1000-50 μg/mL) for 48 h. The results suggested that β-wollastonite can be a low cost bioactive material, which can be useful in biomedical applications.