Hofmeister Effect-Based T1–T2 Dual-Mode MRI and Enhanced Synergistic Therapy of Tumor

The imaging resolution of magnetic resonance imaging (MRI) is influenced by many factors. The development of more effective MRI contrast agents (CAs) is significant for early tumor detection and radical treatment, albeit challenging. In this work, the Hofmeister effect of Fe₂O₃ nanoparticles within the tumor microenvironment was confirmed for the first time. Based on this discovery, we designed a nanocomposite (FePN) by loading Fe₂O₃ nanoparticles on black phosphorus nanosheets. After reacting with glutathione, the FePN will undergo two stages in the tumor microenvironment, resulting in the robust enhancement of r₁ and r₂ based on the Hofmeister effect in the commonly used magnetic field (3.0 T). The glutathione-activated MRI signal of FePN was higher than most of the activatable MRI CAs, enabling a more robust visualization of tumors. Furthermore, benefiting from the long circulation time of FePN in the blood and retention time in tumors, the synergistic therapy of FePN exhibited an outstanding inhibition toward tumors. The FePN with good biosafety and biocompatibility will not only pave a new way for designing a common magnetic field-tailored T₁-T₂ dual-mode MRI CA but also offer a novel pattern for the accurate clinical diagnosis and therapy of tumors.