Magnetic and MRI Contrast Properties of HumAfFt-SPIONs: Investigating Superparamagnetic Behavior and Enhanced T2-Weighted Imaging Performance

The present study introduces a novel theranostic nanoparticle platform that integrates superparamagnetic iron oxide nanoparticles (SPIONs) with a ferritin-based protein nanocage derived from the archaeobacterium Archaeoglobus fulgidus. By exploiting the unique salt-triggered dissociation and reassociation mechanism of the nanocage, SPIONs were successfully encapsulated within the protein's central cavity. The construct thus obtained was characterized by transmission electron microscopy and circular dichroism spectroscopy. The ferritin-coated SPIONs exhibited remarkable superparamagnetic behavior and robust magnetic properties. Characterization using electron paramagnetic resonance and thermal magnetization analysis confirmed the stability of the nanoparticles and their suitability for magnetic hyperthermia applications. Furthermore, T2-weighted magnetic resonance imaging (MRI) demonstrated enhanced contrast, with ferritin-coated SPIONs generating distinct dark-spot imaging, highlighting their efficacy as a contrast agent for advanced biomedical applications.