Asymmetrically Coordinated Dual-Atom Manganese Contrast Agents Enabling High-Efficiency T1 Enhanced MRI for Precise Tumor Visualization.

Achieving atomically precise control over paramagnetic coordination environments is challenging because relaxivity's sixth power dependence on metal water distance demands sub-angstrom precision while also requiring rapid water exchange, two inherently competing requirements in conventional systems. Here, leveraging dual-atom coordination engineering as a rational material design strategy, we successfully synthesized a novel dual-atom manganese-based platform featuring a well-defined asymmetric Mn2-N3O3 geometry anchored on hierarchical boron nitride (Mn-BN). Notably, this atomic-level engineering achieves T1 relaxivity of 36.27 mM-1 s-1 at 3.0 T and 15.86 mM-1 s-1 at 7.0 T, approximately 10-fold higher than those of clinical agents. Combining advanced characterizations with theoretical calculations reveals that adjacent asymmetrically coordinated Mn centers generate cooperative electronic effects that lower water adsorption energy and shorten the Mn-H distance, thereby enhancing water exchange and optimizing dipole-dipole interactions. The Mn-BN exhibits specific magnetic resonance imaging (MRI) T1 signals for accurate tumor boundary visualization, meanwhile preferential hepatocyte uptake through specific transporters creates differential enhancement for sensitive liver metastases detection. This work positions dual-atom coordination engineering as an effective materials design strategy for precise enhancement of MRI properties, providing new opportunities for developing advanced contrast agents with tailored biological interactions and extended imaging windows.