Preparation and characterization of calcium carbonate microspheres and their potential application as drug carriers.

The influence of lecithin from egg yolk (LE) on calcium carbonate (CaCO3) biomineralization was investigated. In the present study, spherical CaCO3 particles were synthesized via coprecipitation in the presence of LE. LE multilamellar liposomes were first tuned by sonication to provide better control over the nucleation of CaCO3. Subsequently, monodisperse microspheres ~2 µm in size were generated by controlling the aggregation and growth of CaCO3 under appropriate concentrations of LE. In contrast to unstable vaterite, the microspheres generated in aqueous solution remained stable for at least 10 days without transforming into calcite, due to the strong interaction between the LE and calcium ions. The microspheres as drug carriers of doxorubicin (DOX) were assessed and were observed to have a good encapsulation efficiency, sustained drug release without a burst release and notable pH sensitivity. In addition, in vivo tumor inhibition examination demonstrated that DOX‑loaded CaCO3 microspheres formulation had more superior efficacy to significantly restrain tumor growth. These novel LE/CaCO3 hybrids may provide novel options for various biomedical applications.