Development of magnetic nanostructured silica-based materials as potential vectors for drug-delivery applications

Metallic iron nanoparticles were synthesized within micron-sized mesoporous molecular sieves (with 2.9-nm pores) and hollow silica microcapsules (pores of 2.7 and 15 nm) using several cycles of wet impregnation under vacuum, followed by drying, oxidation, and reduction steps. For iron-loaded MCM-48, SQUID measurements revealed ferromagnetic behavior at room temperature with a magnetic moment as high as 3.40 emu/g (measured at 2 T) after four deposition cycles. Iron-loaded hollow silica microcapsules (250-nm wall thickness) showed a magnetic moment of 2.40 emu/g (at 2 T) after three deposition cycles and a coercivity as low as 12.9 Oe.