Oxidative Conversion of a Europium(II)-Based T1 Agent into a Europium(III)-Based paraCEST Agent that can be Detected In Vivo by Magnetic Resonance Imaging

Angew Chem Int Ed Engl. 2016 Apr 11;55(16):5024-7. doi: 10.1002/anie.201511649. Epub 2016 Mar 8.


The Eu(II) complex of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) tetra(glycinate) has a higher reduction potential than most Eu(II) chelates reported to date. The reduced Eu(II) form acts as an efficient water proton T1 relaxation reagent, while the Eu(III) form acts as a water-based chemical exchange saturation transfer (CEST) agent. The complex has extremely fast water exchange rate. Oxidation to the corresponding Eu(III) complex yields a well-defined signal from the paraCEST agent. The time course of oxidation was studied in vitro and in vivo by T1-weighted and CEST imaging.

Keywords: T1 weighting; contrast agents; divalent lanthanides; europium; paraCEST.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Contrast Media*
  • Europium / chemistry*
  • Humans
  • Magnetic Resonance Imaging / methods*
  • Oxidation-Reduction


  • Contrast Media
  • Europium