To overcome these limitations, drug delivery techniques have been intensively investigated and studied to improve the therapeutic effect . Compared with conventional formulations, an ideal anticancer drug delivery system shows numerous advantages compared with conventional formulation, selleck chemicals such as improved efficacy, reduced toxicity, and reduced frequency of doses . Besides, the nanocarriers for anticancer drugs can also take advantage of the enhanced permeation and retention (EPR) effect [9–11] in the vicinity of tumor tissues to facilitate the internalization of drugs in
tumors. Drug carriers with diameters AZ 628 less than 600 nm may be taken up selectively by tumor tissues because of the higher permeation of tumor vasculature . Multiplicity carrier and functional nanoparticles exhibit greatly enhanced therapeutic effects and can improve the dispersion stability of the particles in water and endow the particles with long circulation property in vivo[8, 12–18]. However, the nanoscale drug delivery systems may also exhibit some disadvantages, such as poor biocompatibility, incompletely release in vivo, and incomplete degradation. Therefore, people are constantly developing delivery systems which are easily prepared, environment-friendly,
and biocompatible. CaCO3, the most common inorganic material of the nature, widely exists in living creatures and even in some human tissues. There are a large number of reports on calcium carbonate in recent years,
but not so much attention has been focused on its biological effects. Compared with other inorganic materials, CaCO3 has shown promising potential for the development of smart carriers for anticancer drugs  because Carnitine palmitoyltransferase II of its ideal biocompatibility, biodegradability, and pH-sensitive properties, which enable CaCO3 to be used for controlled degradability both in vitro and in vivo. It has been used as a vector to deliver genes, peptide, proteins, and drug [21–23]. Furthermore, spherical CaCO3 particle might be found in its uses in catalysis, filler, separations technology, coatings, pharmaceuticals and agrochemicals [24, 25]. Etoposide, a derivative of the anticancer drug podophyllotoxin, is an important chemotherapeutic agent for the treatment of cell lung cancer , testicular carcinoma , and lymphomas . Its direct applications had been limited by its poor water solubility, side effect for normal tissue, and poor targeting. Therefore, an efficient drug delivery system is desired to overcome these drawbacks and improve its clinical therapy efficiency.