Reactive oxygen species (ROS)-based anticancer therapy methods were heavily dependent on specific tumor microenvironments such as acidity and excess hydrogen peroxide (H2O2). In this work, an acidity-sensitive nanotheranostic agent (FePt@MnO)@DSPE-PEG5000-FA (FMDF NPs) was successfully constructed for MR imaging guided ferroptosis chemodynamic therapy (FCDT) of cancer. The FMDF NPs could specifically target folic acid (FA) receptor-positive tumor cells (HeLa etc.) and induce ferroptosis efficiently by rapidly releasing active Fe2+ to catalyze intracellular H2O2 into ROS based on Fenton reaction. On the other hand, the Mn2+ could also be released due to acidity and further coordinate with GSH to enhance the longitudinal-transverse relaxivity (T1/T2-weighted MR imaging), which could obviously strengthen the contrast distinction between solid tumors and the surrounding tissue to accurately real-time monitor the tumor location. Furthermore, the in vivo anticancer study revealed that the growth of solid tumor models could be suppressed remarkably after treating with FMDF NPs and no obvious damage to other major organs. Therefore, the FMDF NPs were competent simultaneously as an enhanced imaging diagnosis contrast agent and efficient therapy agent for promoting more precise and effective treatment in the bionanomedicine field.
While recent advancements in spin manipulation have utilized topological insulators and non-collinear antiferromagnets confined to two-dimensional films, dimensional limitations have hindered the realization of truly freestanding spin-dependent quantum nanodevices (nm3). Here, we exploit a robust vertical exchange bias confined within core–shell FePt@MnO nanoparticles (D ∼ 9 nm) to control the spin decoherence time of Fe and Mn magnetic atoms. The magnitude (approximately 17% of interfacial spins are fully pinned) and robustness (the pinned spins remain stable even under a negative field of −5 T) of this anomalous exchange bias arise from a coherent interface where strain-induced lattice distortion displaces Mn cations by ångström-scale distances from their equilibrium positions, aligning them with Fe cations. This interfacial coherence enhances interfacial spin–spin exchange coupling─manifested as the anomalous exchange-bias effect─which directly modulates spin decoherence dynamics: τ2 for Mn2+ spins shortens by 9.8% (108.3 ps → 98.5 ps), while Fe spins exhibit a concomitant τ2 enhancement. This work establishes a direct link between spin decoherence time and the exchange-bias effect, offering a pathway for the coherent engineering of quantum nanomaterials.
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