Self-Assembly and Shape Control of Hybrid Nanocarriers Based on Calcium Carbonate and Carbon Nanodots

We describe a platform for the synthesis of functional hybrid nanoparticles in the submicrometer range with tailorable anisotropic morphology. Fluorescent carbon dots (CDs) and poly­(acrylic acid) (PAA) are used to modify the crystallization and assembly of calcium carbonate (CaCO₃). Carboxylic groups on CDs sequester calcium ions and serve as templates for CaCO₃ precipitation when carbonate is added. This creates primary CaCO₃ nanoparticles, 7 nm in diameter, which self-assemble into spheres or rods depending on the PAA concentration. At increasing polymer concentration, oriented assembly becomes more prevalent yielding rod-like particles. The hybrid particles show colloidal stability in cell medium and absence of cytotoxicity as well as a loading efficiency of around 30% for Rhodamine B with pH-controlled release. Given the morphological control, simplicity of synthesis, and efficient loading capabilities the CD-CaCO₃ system could serve as a novel platform for advanced drug carrier systems