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 One-tuning the core size and PEG coating of SPIOs, the T-2 relaxivity per particle can be increased by >200-Fold. With 14 nm core and PEG1000 coating, SPIOs can have T-2 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.