Fig. 4.

Schematic illustration of synthetic strategies to prepare different CaP nanocarriers. A) the “Mix-CaP” is prepared by mixing various materials directly; B) the hybrid CaP nanoparticles with a “Polymer-Shell” are prepared by “one-pot” method; C) the multifunctional CaP nanoparticles with a “Lipid-Shell” are prepared by micro-emulsion method; D) the “Muti-Layer” CaP nanoparticles are prepared by a layer-by-layer method and E) the “CaP-Shell” CaP nanoparticles are prepared by the external precipitation on the core of polymer or inorganic.