Coating Optimization of Superparamagnetic Iron Oxide Nanoparticles for High T2 Relaxivity

We describe a new method for coating superparamagnetic iron oxide nanoparticles (SPIOs) and demonstrate that, by fine-tuning the core size and PEG coating of SPIOs, the T2 relaxivity per particle can be increased by >200-fold. With 14 nm core and PEG1000 coating, SPIOs can have T2 relaxivity of 385 s−1 mM−1, which is among the highest per-Fe atom relaxivities. In vivo tumor imaging results demonstrated the potential of the SPIOs for clinical applications.