A Janus Chelator Enables Biochemically Responsive MRI Contrast with Exceptional Dynamic Range

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• 作者：Eric M. Gale ; Chloe M. Jones ; Ian Ramsay ; Christian T. Farrar ; Peter Caravan
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：December 14, 2016
• 年：2016
• 卷：138
• 期：49
• 页码：15861-15864
• 全文大小：315K
• ISSN：1520-5126

文摘

We introduce a new biochemically responsive Mn-based MRI contrast agent that provides a 9-fold change in relaxivity via switching between the Mn³⁺ and Mn²⁺ oxidation states. Interchange between oxidation states is promoted by a “Janus” ligand that isomerizes between binding modes that favor Mn³⁺ or Mn²⁺. It is the only ligand that supports stable complexes of Mn³⁺ and Mn²⁺ in biological milieu. Rapid interconversion between oxidation states is mediated by peroxidase activity (oxidation) and l-cysteine (reduction). This Janus system provides a new paradigm for the design of biochemically responsive MRI contrast agents.