In Situ Strategy to Encapsulate Antibiotics in a Bioinspired CaCO₃ Structure Enabling pH-Sensitive Drug Release Apt for Therapeutic and Imaging Applications

Herein we demonstrate a bioinspired method involving macromolecular assembly of anionic polypeptide with cationic peptide-oligomer that allows for in situ encapsulation of antibiotics like tetracycline in CaCO3 microstructure. In a single step one-pot process, the encapsulation of the drug occurs under desirable environmentally benign conditions resulting in drug loaded CaCO3 microspheres. While this tetracycline-loaded sample exhibits pH dependent in vitro drug-release profile and excellent antibacterial activity, the encapsulated drug or the dye-conjugated peptide emits fluorescence suitable for optical imaging and detection, thereby making it a multitasking material. The efficacy of tetracycline loaded calcium carbonate microspheres as pH dependent drug delivery vehicles is further substantiated by performing cell viability experiments using normal and cancer cell lines (in vitro). Interestingly, the pH-dependent drug release enables selective cytotoxicity toward cancer cell lines as compared to the normal cells, thus having the potential for further development of therapeutic applications.