Magnetic properties and T2-Weighted MR images

Results show no remanence and coercivity, approving the superparamagnetic property of the nanoprobe (fig 5a). According to Fig. 5b, it is clear, as the concentrations of SPION-CDs are increased, the signal intensities are decreased. As shown in Fig. 5c, the relaxivity value (r2) of SPION-CDs is evaluated to be 308.5 mM-1.s-1 from the slope of the concentration-dependent relaxation rate and the R2 is enhanced as the concentrations increase, indicating the ability of this nanoparticle to serve as an effective T2 MRI contrast agent. It is clear that the signal enhancement of OVCAR-3 cells treated with nanoprobe is much greater than of HeLa cells with similar iron concentration, which is consistent with a preferential uptake by STIP1 overexpressed cells (Fig. 5d).