Supercritical-Fluid-Assisted One-Pot Synthesis of Biocompatible Core(γ-Fe2O3)/Shell(SiO2) Nanoparticles as High Relaxivity T2-Contrast Agents for Magnetic Resonance Imaging

• Published in: Advanced functional materials 2009-07, Vol.19 (14), p.2319-2324
• Main Authors: Taboada, Elena, Solanas, Raul, Rodríguez, Elisenda, Weissleder, Ralph, Roig, Anna
• Format: Article
• Language: English
• Subjects: biomedical applications; composite materials; core/shell nanoparticles; iron oxide; magnetic materials; silica; supercriticial fluid
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.200801681

Monodisperse iron oxide/microporous silica core/shell composite nanoparticles, core(γ‐Fe2O3)/shell(SiO2), with a diameter of approximately 100 nm and a high magnetization are synthesized by combining sol–gel chemistry and supercritical fluid technology. This one‐step processing method, which is easily scalable, allows quick fabrication of materials with controlled properties and in high yield. The particles have a specific magnetic moment (per kg of iron) comparable to that of the bulk maghemite and show superparamagnetic behavior at room temperature. The nanocomposites are proven to be useful as T2 MRI imaging agent. They also have potential to be used in NMR proximity sensing, theranostic drug delivery, and bioseparation. A supercritical‐fluid‐assisted sol–gel processing method is used to fabricate monodisperse magnetic core/shell nanoparticles (NPs). The initial sol containing the γ‐Fe2O3 NPs at ambient conditions (left) is combined with a silica source. After treatment at supercritical conditions, the expanded sol contains gel composite particles (middle). TEM images of the magnetic composite material clearly reveal nuclei surrounded by silica shells (right).