Phospholipid Encapsulation and Surface Functionalization of Superparamagnetic Iron Oxide Nanoparticles for Molecular Magnetic Resonance Imaging: Effects on Spin-Spin Proton Relaxation

Superparamagnetic iron oxide (SPIO) nanoparticles are prevalent as nanoprobes for molecular magnetic resonance imaging (MRI), providing negative contrast by locally affecting the spin-spin (T2) proton relaxation of water. SPIO nanoparticles are typically Fe3O4 nanocrystals and are commonly used as a negative MRI contrast agent, implementing various surface functionalization techniques to provide molecular targeting to biological macromolecules. The authors recently demonstrated molecular MRI (Figure 1) of epidermal growth factor receptor (EGFR), an extensively studied oncoprotein, in human prostate and head-and-neck cancer cell lines using monoclonal antibodies covalently conjugated to phospholipid micelle encapsulated 12 nm single crystalline SPIO nanoparticles, demonstrating molecular targeting capabilities via surface functionalization [1].