Ferrocene‐Functionalized Black Phosphorus Nanoplatform Enables Targeted and Prolonged MRI Visualization of Atherosclerotic Plaques

Abstract Despite the critical role of contrast‐enhanced magnetic resonance imaging (MRI) in clinical diagnostics, current contrast agents face dual challenges: metallic formulations provoke biosafety concerns while organic radicals exhibit transient imaging windows. To overcome these limitations, a radical‐engineered 2D black phosphorus (2D BP) nanoplatform is reported through atomic‐scale conjugation of aminoferrocene, creating a stable complex with enhanced electron spin resonance, named FcP. The covalent coupling strategy establishes persistent T ₂ ‐weighted contrast capability. Subsequent hyaluronic acid (HA) functionalization endows the HA‐FcP system with CD44‐specific targeting, achieving 1.7‐fold higher plaque accumulation than non‐targeted counterparts in apolipoprotein E‐deficient models. Remarkably, this nanostructure enables continuous MRI visualization of atherosclerotic lesions for 120 h post‐injection. Systematic biosafety evaluation demonstrates >90% cell viability and normal hematological parameters. This work pioneers a new paradigm for MRI contrast agents through spin state manipulation of 2D materials, providing a translational platform for precision cardiovascular diagnostics.