Biological properties study of bioactive diopside containing 0.5wt% Na2CO3 prepared from local raw materials

Abstract

This study initially focused on synthesizing diopside (CaMgSi2O6) using the solid-state

sintering method, starting with locally sourced dolomite (CaMg(CO3)2) and low-cost laboratory- grade silicon dioxide (SiO2). The preparation process was carried out at a temperature of 1250°C

for two hours through two mechanisms: one without additives and the other with the addition of 0.5% sodium carbonate. The sintered samples were characterized using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). Results demonstrated an improvement in crystallization and sintering behavior with the addition of sodium carbonate (Na2CO3) , reflecting enhanced sintering performance. It was also confirmed that sodium was incorporated into the diopside without forming any secondary phases (Bioactive glasses). Following the synthesis, the samples were crushed and subjected to bioactivity testing. This evaluation involved immersing diopside granules in simulated body fluid (SBF) for varying durations to examine the initiation and growth of apatite on their surfaces. The effect of sodium carbonate (Na2CO3) on the biological properties of diopside was investigated by analyzing the chemical composition using FTIR after immersion periods of 4 hours, 1 day, 4, 7, and 11 days. The findings indicated distinct differences in the partial dissolution behavior of the diopside granules during the early stages of immersion between samples with and without sodium carbonate addition. This variability was attributed to the role of sodium cations as network modifiers, reducing surface resistance to degradation in physiological fluids. Consequently, sodium addition significantly enhanced apatite nucleation and accelerated the formation of carbonate hydroxyapatite layers on sample surfaces compared to those without additives. Furthermore, the samples containing sodium carbonate exhibited greater apatite deposition compared to pure diopside counterparts. Therefore, the study concluded that sodium carbonate acts as a bioactivity enhancer in diopside, improving their biological performance, particularly in terms of bioactive properties.