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 CaCO(3)/Fe(3)O(4) composite nanoparticles and cationic surfactant double templates. Fe(3)O(4) nanoparticles were first mixed into CaCO(3) using rotating packed bed forming CaCO(3)/Fe(3)O(4) composite nanoparticles. Tetraethoxysilane was then added as precursor to form silica layer on the surface of CaCO(3)/Fe(3)O(4) 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 CaCO(3), 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. (c) 2008 American Institute of Physics.