Influence of EDTA and EGTA on the Eu(III)/Cm(III) speciation in the human digestive system

In mining and industrial areas involved in lanthanide (Ln) production, both environment and population show increased Ln concentrations. To lower the health risks of these heavy metal ions on the affected persons by decreasing the Ln concentration in the human body, chelation therapy is used as decorporation strategy. Chelation therapy is also an important tool for radiation protection. The aminopolycarboxylic acid diethylenetriaminepentaacetic acid (DTPA) is the only clinical approved decorporation agent against actinides (An). However, DTPA is not equally efficient for all An and can be also toxic at higher concentrations.
Therefore, we comprehensively studied the complexation behaviour of DTPA related compounds such as ethylenediaminetetraacetic acid (EDTA) and ethylene glycol-bis(β-aminoethyl ether)-N,N,N’,N’-tetraacetic acid (EGTA) with trivalent europium and curium by combining spectroscopy and isothermal titration calorimetry. The influence of these ligands on the speciation of Eu(III) in the simulated human digestive system has been determined on a molecular level using time-resolved laser-induced fluorescence spectroscopy (TRLFS). Furthermore, the ligands were successfully synthesised in their deuterated form to perform 2H-NMR spectroscopy to overcome the large 1H-NMR background occurring from organic molecules such as proteins and enzymes in the artificial digestive system. These investigations contribute to an advanced understanding of the molecular processes in chelation therapy and its further development in the future.
This work is funded by the German Federal Ministry of Education and Research (BMBF) under grant number 02NUK057A and is part of the joint project RADEKOR.