Endohedral Metallofullerenes, Iron Oxide Agents, and Gold Nanoparticles for Brain Imaging

Recent advancements in nanotechnology have revolutionized medical imaging and therapeutics by introducing a wide range of nanomaterials. These nanoparticles possess exceptional properties such as increased surface area, enhanced optical characteristics, and improved mechanical and magnetic properties. They can be categorized based on their size, shape, and nature. Nanoparticles have exhibited promising results in enhancing the sensitivity of magnetic resonance imaging (MRI), overcoming the limitations of optical imaging techniques, and improving drug delivery through the blood–brain barrier. Specifically, gadolinium (Gd)-based metallofullerenes (MFs) and iron oxide nanoparticles have shown immense potential for MRI, while gold nanoparticles (GNPs) have demonstrated remarkable photothermal properties for therapy. The development of targeted molecular imaging agents and multifunctional nanoprobes has further expanded the scope of their applications. Gadolinium-based endohedral MFs have emerged as particularly noteworthy nanomaterials, offering significant MRI relaxivity properties compared to conventional Gd chelates, with enhancements of up to 20 times (Mikawa, Bioconjugate Chemistry 12: 510–514, 2001) and 30 times (Fatouros, Radiology 240: 756–764, 2006). The relaxivity mechanism of these metallofullerenes differs from that of classical Gd chelates as it relies on the electronic interactions between the fullerene cage and water molecules, instead of internal water interactions. This unique property enhances water solubility and optimizes the magnetic coupling between Gd3+ unpaired electrons and external water protons. Moreover, the presence of hydroxyl groups on the surface facilitates proton exchange, further expanding their potential applications in tumor treatment and antioxidant activity. Overall, these advancements in nanomaterials hold tremendous promise in revolutionizing medical imaging and therapeutics.