Magnetic mesoporous silica nanospheres as DNA/drug carrier

In this study, superparamagnetic magnetite/polystyrene (Fe(3)O(4)/PS) nanospheres obtained by miniemulsion polymerization have been encapsulated with a thin nonporous silica coating as well as an additional layer of ordered mesoporous silica through a cetylmethyl ammonium bromide (CTAB) templated sol-gel process. The obtained sandwich-like magnetic mesoporous silica nanospheres (M-MSNs) show high magnetization accompanied with typical ordered mesoporous material characteristics, including ordered and accessible mesopores of 4.2 nm in size, high surface area (475 m(2)/g) and high pore volume (0.6 cm(3)/g). The composite nanospheres also possess monodisperse spherical morphology with a smooth surface, and narrow particle size distribution centered at 225 nm. Adsorption tests of macromolecular salmon sperm DNA and the small-molecular drug rapamycin on the M-MSNs both show high adsorption capacity, demonstrating their promising applicability in enhanced DNA separation or drug/gene delivery. (C) 2011 Elsevier B.V. All rights reserved.