Fabrication of magnetic porous hollow silica drug carriers using CaCO₃/Fe₃O₄ composite nanoparticles and cationic surfactant double templates

Magnetic porous hollow silica nanosphere is a new class of structured nanomaterials for drug delivery. In this paper, we report a synthesis of magnetic porous hollow silica nanospheres (MPHSNs) using CaCO₃/Fe₃O₄ composite nanoparticles and cationic surfactant double templates. Fe₃O₄ nanoparticles were first mixed into CaCO₃ using rotating packed bed forming CaCO₃/Fe₃O₄ composite nanoparticles. Tetraethoxysilane was then added as precursor to form silica layer on the surface of CaCO₃/Fe₃O₄ composite nanoparticles, while hexadecyltrimethylammonium bromide was used as a second template to direct the formation of porous silica shells. After the calcination of the surfactants and etching away CaCO₃, MPHSNs were formed with the magnetite nanoparticles remaining in the cores. Transmission electron microscopy was applied for the nanostructure determination. The pore size can be measured by micromeritics analyzer. Magnetic properties of MPHSNs were measured by a superconducting quantum interface device. Zero-field-cooled and field-cooled magnetization data in the temperature range of 5–300 K show that the MPHSNs are superparamagnetism above the blocking temperature and ferromagnetism below the blocking temperature after the calcination. The MPHSNs can be used as potential nanocarriers for targeted delivery and controlled releasing.