Figure 1.

Nanomaterials and MRI contrast agents for cancer theranostics. (a) Size scaling of nanomaterials (e.g., liposomes, nanoparticles) and MRI contrast agents in relation to their extravasation when injected systemically. It is generally believed that in cancer the vasculature is more leaky [7]. Drug and/or SPIO can be encapsulated into nanomaterials. (b) Spinel ferrite structure showing tetrahedral and octahedral sites. There are 64 tetrahedral and 32 octahedral positions that are available for cations in one ferrite unit cell. However 12.5% and 75% of the tetrahedral and octahedral sites, respectively, are occupied by cations. See [14] for details.