Fabrication of fluorescent microparticles by doping water-soluble CdTe nanocrystals into calcium carbonate for monitoring intracellular uptake

3-Mercaptopropyl acid (MPA) capped CdTe quantum dots (QDs) were embedded into CaCO3 microparticles with a size of 1.4–4.4 μm by addition of the QDs into Ca(NO3)2 solution during a mineralization process. Compared to the parent QDs, about 1/7–1/3 photoluminescence efficiency of the embedded QDs was preserved, enabling the CaCO3(CdTe) particles visible under UV irradiation. The structure and morphology of the CaCO3(CdTe) particles were characterized by X-ray diffraction (XRD), UV–vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Protected by the CaCO3 particles, the QDs in the composites were more stable against long term storage, UV irradiation and cell culture medium containing serum. The CaCO3(CdTe) particles could be internalized into live cells, human liver cancer cells (HepG2), for example, and most of which distributed in the lysosomes as revealed by confocal microscopy. Also the CaCO3(CdTe) particles had low cytotoxicity in comparison with the parent CdTe QDs.