Tannylated Calcium Carbonate Materials with Antacid, Anti-Inflammatory, and Antioxidant Effects

Calcium carbonate (CaCO₃)-based materials have received notable attention for biomedical applications owing to their safety and beneficial characteristics, such as pH sensitivity, carbon dioxide (CO₂) gas generation, and antacid properties. Herein, to additionally incorporate antioxidant and anti-inflammatory functions, we prepared tannylated CaCO₃ (TA-CaCO₃) materials using a simple reaction between tannic acid (TA), calcium (Ca²⁺), and carbonate (CO₃^2-) ions. TA-CaCO₃ synthesized at a molar ratio of 1:75 (TA:calcium chloride (CaCl₂)/sodium carbonate (Na₂CO₃)) showed 3-6 μm particles, comprising small nanoparticles in a size range of 17-41 nm. The TA-CaCO₃ materials could efficiently neutralize the acid solution and scavenge free radicals. In addition, these materials could significantly reduce the mRNA levels of pro-inflammatory factors and intracellular reactive oxygen species, and protect chondrocytes from toxic hydrogen peroxide conditions. Thus, in addition to their antacid property, the prepared TA-CaCO₃ materials exert excellent antioxidant and anti-inflammatory effects through the introduction of TA molecules. Therefore, TA-CaCO₃ materials can potentially be used to treat inflammatory cells or diseases.