Transition metal molecular clusters hold great promise as magnetic resonance imaging (MRI) probes, where careful chemical design can afford control over the size, shape, and total spin state of the contrast agent (CA). Although such clusters can act as a single entity, exhibiting advanced in situ reactivity to key diagnostic biomolecules, their dissociation/speciation in biological media hinders their potential as MRI CAs. To resolve this, the N-2-pyrimidylimidoyl-2-pyrimidylamidine chelate was employed to selectively bind 3d metal ions, forming highly stable mixed-metal clusters. Through spectroscopic, electrochemical, and magnetic analysis, along with in vitro and in vivo studies, the application of iron and manganese homo- and heterometallic complexes as MRI CAs capable of mapping tumor redox status through a simple T₁w/T₂w ratiometric approach was demonstrated. The use of heteropolynuclear 3d super-atomic complexes suitable for semi-quantitative in vivo MRI of tissue redox status opens new avenues for non-invasive characterization of biochemical microenvironments by MRI.

中文翻译：

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基于整束的氧化还原反应性超原子 MRI 造影剂


过渡金属分子簇作为磁共振成像 （MRI） 探针具有很大的前景，其中仔细的化学设计可以控制造影剂 （CA） 的大小、形状和总自旋状态。尽管此类簇可以充当单个实体，对关键诊断生物分子表现出高级原位反应性，但它们在生物培养基中的解离/物种形成阻碍了它们作为 MRI CA 的潜力。为了解决这个问题，采用 N-2-嘧啶酰亚胺酰-2-嘧啶螯合物选择性结合 3d 金属离子，形成高度稳定的混合金属簇。通过光谱、电化学和磁学分析，以及 体外和 体内研究，证明了铁和锰同金属和异金属配合物作为 MRI CA 的应用，能够通过简单的 T₁w/T₂w 比率方法绘制肿瘤氧化还原状态。使用适用于组织氧化还原状态的半定量体内 MRI 的异多核 3d 超原子配合物为通过 MRI 对生化微环境进行无创表征开辟了新的途径。