Dry Ice Carbonation Approach for the Synthesis of Calcium Carbonate-Based Magnetic Composites

Abstract

Multimodal magnetic materials have emerged as a promising class of materials for biomedical applications due to their ability to seamlessly integrate diverse functionalities into a single domain. This versatility enables their use in a wide range of applications including targeted drug delivery, cell labelling and bioimaging. Herein, we report the synthesis and characterisation of calcium carbonate (CaCO3)-coated magnetite (Fe3O4) particles using a novel, low temperature, dry ice carbonation approach, both in aqueous and solvent-free conditions. The procedure involves coating Fe3O4 nanoparticles with poly(sodium 4-styrenesulfonate) (PSS), followed by further functionalisation with a porous CaCO3 outer shell. Both approaches produce superparamagnetic composites. However, an aqueous approach produces rhombohedral calcite structures with an average size of ~0.7 μm, while a solvent-free approach results in the formation of unique acicular microstructures approximately 1 μm in size, which consist of all three anhydrous polymorphs of CaCO3. The potential of the composites for use as drug carriers is also investigated, with their loading and release of a cationic dye monitored using UV-Vis spectroscopy. The unique magnetic properties of Fe3O4 nanoparticles combined with the biocompatibility and high drug loading capacity of CaCO3 results in new materials with strong potential for applications in biomedicine, including targeted drug delivery.