Open AccessEight-Coordinate, Stable Fe(II) Complex as a Dual 19F and CEST Contrast Agent for Ratiometric pH Imaging
Author(s) -
Kriti Srivastava,
Giuseppe Ferrauto,
Victor G. Young,
Silvio Aime,
Valérie C. Pierre
Publication year - 2017
Publication title -
inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 233
eISSN - 1520-510X
pISSN - 0020-1669
DOI - 10.1021/acs.inorgchem.7b01629
Subject(s) - chemistry , contrast (vision) , nuclear magnetic resonance , saturation (graph theory) , signal (programming language) , analytical chemistry (journal) , chromatography , optics , physics , mathematics , combinatorics , computer science , programming language
Accurate mapping of small changes in pH is essential to the diagnosis of diseases such as cancer. The difficulty in mapping pH accurately in vivo resides in the need for the probe to have a ratiometric response so as to be able to independently determine the concentration of the probe in the body independently from its response to pH. The complex Fe II -DOTAm-F12 behaves as an MRI contrast agent with dual 19 F and CEST modality. The magnitude of its CEST response is dependent both on the concentration of the complex and on the pH, with a significant increase in saturation transfer between pH 6.9 and 7.4, a pH range that is relevant to cancer diagnosis. The signal-to-noise ratio of the 19 F signal of the probe, on the other hand, depends only on the concentration of the contrast agent and is independent of pH. As a result, the complex can ratiometrically map pH and accurately distinguish between pH 6.9 and 7.4. Moreover, the iron(II) complex is stable in air at room temperature and adopts a rare 8-coordinate geometry.