Cubic Zinc-Doped Iron Oxide Nanoparticles with Poly(Ethylene Glycol) or Sodium Citrate Surface Coatings for Tumor Imaging

Magnetic resonance imaging (MRI) has been extensively studied over the past few decades, so developing strategies to enhance the T-2 contrast is of significant importance. Herein, we synthesized a series of cubic zinc-doped iron oxide nanoparticles (CZINs) with different dopant ratios by the thermal decomposition method. CZINs with a dopant ratio of 1:5 show the best magnetic performance and T-2 relaxivity among all CZINs. More importantly, we demonstrate that differentiated surface modifications lead to diverse in vivo behavior of CZINs, resulting in the distinct contrast efficiency for different types of tumor. Compared to sodium citrate (SC)-modified CZINs, polyethylene glycol (PEG)-modified CZINs show lower protein absorption, longer blood circulation time, and lower uptake amount in liver. These behavior differences lead PEG-modified CZINs to be potential candidates for assisting precise subcutaneous tumor diagnosis, while SC-modified CZINs are more suitable for achieving accurate liver metastases imaging. This research holds significant promise to develop potential T-2 contrast agents, which can be translated into clinical practice.