Figure 3.

A schematic illustration of the synthesis of magnetic mesoporous silica nanoparticles by different methods. (i) Synthesis using an oil-in-water technique. Hydrophobic-ligand-capped iron oxide nanoparticles dispersed in a nonpolar organic solvent are added to an aqueous solution containing cetyltrimethylammonium bromide (CTAB) and TEOS, allowing the formation of core–shell magnetic mesoporous silica nanoparticles (M-MSNs). Adapted with permission from reference [51]. Copyright (2006) American Chemistry Society. (ii) Synthesis using a water-in-oil method. The synthesis starts with micellular solution of an amphiphilic surfactant (such as Igepal CO-520), and core–shell iron oxide nanoparticle@nSiO₂ (IONP@nSiO₂) with a reverse-microemulsion system formed on the addition of ammonia. Finally, the core–shell M-MSNs are produced by the introduction of an additional mesoporous silica shell (mSiO₂). (iii) Synthesis using a hard-templating strategy. This method starts with the introduction of mesoporous silica structures on the surface of native iron oxide nanoparticles by adding the silica source and the pore directing agent (e.g., TEOS and cetyltrimethylammonium salt). The desired M-MSNs are produced after calcination to remove the embedded surfactant template. Adapted with permission from reference [54]. Copyright (2009) The Royal Society of Chemistry.