Utilizing CO2 for ultrafast mechanosynthesis of calcite with potential pharmaceutical applications as a sustained-release medicine

In this study, we investigate the use of gaseous CO 2 for the mechanochemical synthesis of calcite, a material with sustained calcium ion release properties, making it suitable for pharmaceutical applications. Solid CaO and gaseous CO 2 were used as reactants, while the reactivity between them was tested in the absence and presence of liquid H 2 O. Milling for 1 minute at 150 rpm showed no reaction without water, while water addition led to the calcite formation. The mechanosynthesized calcite was characterized and compared to natural eggshell and commercial pharmaceutical drug. Mechanosynthesized calcite exhibited a crystallite size of 290 nm, the smallest mean particle size at 567 nm, and the highest specific surface area at 8.6 m²/g. Thermal analysis confirmed its high purity. Dissolution tests of 500 mg calcite tablets in simulated gastric fluid (SGF; pH 1.2) at body temperature (37 ± 0.5 °C) showed differences in calcium release profiles. First-order kinetic model best described eggshell (R² = 0.9804) and pharmaceutical calcite (R² = 0.9932), the Korsmeyer-Peppas model fit mechanosynthesized calcite (R² = 0.9953). Further, calcium influx was tested on osteoblast SAOS-2 and HeLa cells exposed to SGF dissolved calcite solution using fluorimetric analysis and fluorescence microscopy. Results suggest that mechanosynthesized calcite may be more effective for pharmaceutical use compared to other sources, offering potential advantages in medication development. • Mechanically induced carbonation. • CO 2 utilization during mechanosynthesis. • Calcite formation in 1 min. • Sustained-release effect of mechanocarbonized calcite. • Comparison of three calcite sources: mechanosynthesized, eggshell, and drug.