Structural investigation of Neptunium (IV) in toxicological processes
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0893-JJ09-01.1
Structural investigation of Neptunium (IV) in toxicological processes C. Den Auwer, P. Moisy and D. Guillaumont, CEA Marcoule, DEN/DRCP/SCPS, 30207 Bagnols sur Cèze Cedex, France. C. Vidaud CEA Marcoule, DSV/DIEP/SBTN, 30207 Bagnols sur Cèze Cedex, France. H. Funke, C. Hennig Forshungszentrum Rossendorf, Institute of Radiochemistry, P.O. Box 510119, D-01314 Dresden, Germany and Rossendorf Beamline at the European Synchrotron Radiation Facility, F38043 Grenoble, France.
ABSTRACT
General understanding needs to be deepened of intramolecular interactions engaged in molecular actinide species, i.e. physical chemical mechanisms that drive the affinity of chelating ligands for actinide cations still needs to be deepened. In this field, X ray Absorption Spectroscopy has been extensively used as a structural and electronic metal cation probe. Combination with more traditional spectroscopic techniques such as spectrophotometry is an ideal tool for the understanding of the chelation mechanism. Metallobiomolecules are considered elaborate inorganic complexes with well-designed metal active sites. Although the various interaction processes between essential cations important to biology and proteins are widely studied, focus on the actinides is more seldom. Actinide impact on biological cycles has been motivated by risk assessments related to the wide use of nuclear fuel sources and industrial or military applications. In particular, the interactions of these cations with the biologically active complexation sites are only partially understood.
INTRODUCTION
In the field of human toxicology, internal contamination with actinides under either acute or chronic conditions has the potential to induce both radiological and chemical toxicity. Whatever the route of contamination is (inhalation, ingestion or wound), the radionuclide is absorbed into, and then transported by the blood fluid (the absorption rate depends on the dissolution properties of the initial physico-chemical form) prior to deposition in the target organs (e.g., bone, kidney, liver) in which it is stored and then slowly eliminated through urines and faeces. Speciation studies, which refer to the distribution of species in a particular medium, are necessary to improve the description, understanding and prediction of actinide trace element behavior and toxicity. It may also have an important input to decorporation studies or treatment of the contamination by providing guidance on the structure, affinity and design of potential specific chelating agents synthesized and used for the elimination of an incorporated radionuclide. At the molecular level, general understanding of the interactions engaged in actinide adducts, i.e. physical chemical mechanisms that drive the affinity of possible
0893-JJ09-01.2
coordination sites for actinide cations still needs to be deepened. As a result, the intramolecular interactions of actinide elements with either smart chelates designed for coordination and bioinorganic chemistry or naturally occurring chelating agen
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