19F PARASHIFT Probes for Magnetic Resonance Detection of H2O2 and Peroxidase Activity

Elevated levels of reactive oxygen species and peroxidase expression are often associated with inflammation and inflammatory diseases. We developed two novel Co­(II) complexes that can be used to detect oxidative activity associated with inflammation using 19F magnetic resonance imaging (MRI). These agents display a large change in 19F chemical shift upon oxidation from Co­(II) to Co­(III), facilitating selective visualization of both species using chemical shift selective pulse sequences. This large chemical shift change is attributed to a large magnetic anisotropy in the high spin Co­(II) complexes. Importantly, the differing reactivity of the two agents allows for detection of either H2O2 production and/or the activity of peroxidase enzymes, providing two useful platforms for 19F MR hot spot imaging of oxidative events associated with biological inflammation.活性氧（reactive oxygen species）与过氧化物酶（peroxidase）表达水平升高，常与炎症及炎症性疾病密切相关。本研究开发了两种新型二价钴（Co(II)）配合物，可借助19F磁共振成像（19F magnetic resonance imaging, MRI）检测与炎症相关的氧化活性。这类探针在从二价钴氧化为三价钴（Co(III)）的过程中，会出现显著的19F化学位移（chemical shift）变化，可通过化学位移选择性脉冲序列（chemical shift selective pulse sequences）实现两种价态钴物种的选择性可视化。这种显著的化学位移变化，源于高自旋（high spin）二价钴配合物所具备的大磁各向异性（magnetic anisotropy）。尤为关键的是，两种探针的反应活性存在差异，可分别检测过氧化氢（H₂O₂）的生成量或过氧化物酶活性，为与生物炎症相关的氧化事件提供了两套实用的19F磁共振热点成像（hot spot imaging）平台。