Advanced CaCO₃-derived delivery systems for bioactive compounds

Calcium carbonate (CaCO₃) has long been used as a delivery system owing to its wide availability, biocompatibility, and degradability. However, it often suffers from many challenges toward rapid dissolution at stomach acid environment, low retention ability, and lack of sustained release. Many of these issues can be addressed by modifying the CaCO₃ particles or integrating them with other encapsulation systems, generating advanced CaCO₃-derived systems. This review article presents a recent progress (2015-2022) in the utilization of CaCO₃ particles in the exploration of various advanced delivery systems, including polymer-doped CaCO₃, surface-coated CaCO₃, CaCO₃-stabilized Pickering emulsions, CaCO₃-in-hydrogels, and liposomal CaCO₃. Some emerging systems templated on CaCO₃ sacrificial cores, such as hollow capsules, matrix-type capsules, and core-shell capsules, are also reviewed. A brief description of each system is given, and then their formation, structure, and properties are described. Particular emphasis is given to the applications and challenges of these advanced systems for the protection and controlled delivery of bioactive compounds in the biological, pharmaceutical, and functional food fields.