Potent dual-mode hyperthermia and chemodynamic therapy triggered by smart magnetic ring-shaped nanozymes under switchable T1–T2 MRI navigation

Emerging nanotechnologies in cancer therapy increasingly highlight the importance of integrating therapeutic and diagnostic functions into a single platform for enhanced efficacy and real-time monitoring. Here, we present a vortex‐shaped nanoring Fe 3 O 4 @MnO 2 @PDA (polydopamine) engineered for dual‐mode T 1 – T 2 magnetic resonance imaging (MRI)‐guided, dual‐thermal, and Fenton‐like chemodynamic therapy (CDT). The ring‐shaped nano Fe 3 O 4 core provides magnetothermal hyperthermia, while the MnO 2 layer, acting as a responsive nanozyme, catalyzes endogenous H 2 O 2 to generate oxygen and bolster CDT. Meanwhile, the PDA coating efficiently absorbs near‐infrared light, amplifying photothermal effects for tumor ablation. Under dual‐heating conditions, the temperature rise rate (2.05–2.92 times) and final equilibrium temperatures (1.57–2.27 times) exceed those of single‐mode heating, underscoring a robust synergistic effect. Additionally, due to the shell’s shielding effect weakening T 2 signals and the tumor microenvironment enhancing T 1 relaxation, the T 1 (5.75 Mm −1 s −1 ) to T 2 (91.56 mM −1 s −1 ) ratio is optimized specifically at tumor sites, thus achieving effective dual‐modal MRI contrast. Moreover, the smart MnO 2 design not only furnishes dynamic imaging enhancements but also enables environment‐triggered Mn 2+ release, offering further diagnostic and therapeutic benefits. In vitro and in vivo evaluations confirm significant tumor suppression with minimal systemic toxicity. These findings position nanoring Fe 3 O 4 @MnO 2 @PDA as a promising dual‐mode MRI‐guided, dual‐thermal, and chemodynamic platform for advanced cancer therapy.