Influence of media on the matured calcite-to-vaterite phase transformation in the presence of Symphytum officinale

Abstract

Considerable research has been dedicated to developing micro-/nano-sized calcium carbonate (CaCO₃) particles due to their wide range of applications in both industrial and biomedical fields. Many synthesis methods require organic solvents, which are harmful to the environment. Herein, we presented an in vitro biomimetic CaCO₃ synthesis route using a simple precipitation method that is cost-efficient, fast, and easy to perform in different media (Milli-Q water, simulated body fluid, and artificial seawater). We investigated the transformation of the most stable phase (calcite) into the less stable phase (vaterite) in the presence of comfrey (Symphytum officinale). The rhombohedral calcite morphology transitioned into the roughly spherical morphology of vaterite in Milli-Q water. The formed vaterite maintained its morphology for an extended period without requiring special storage conditions. Due to the high stability of vaterite nano–microparticles, they are expected to have broader applications across diverse research fields.