Ph.D. projects

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Engineering Advanced Chelators for Actinide Decorporation: Synthesis and Characterization

Jason Ross

Dr. Moritz Schmidt, Dr. Robert Gericke, Dr. Peter Kaden (HZDR)

Chemistry of the f-elements

05/2024-06/2027

The highly radiotoxic actinides (An), including thorium (Th), uranium (U), neptunium (Np), plutonium (Pu), americium (Am), and curium (Cm), have been used in various applications over the past 75 years. These radionuclides occur naturally or are released during nuclear activities, posing significant health risks upon internal exposure. Current treatments, such as decorporation therapy with CaNa₃(DTPA), have limited efficacy and associated toxicities. The ActiDecorp project seeks to develop more effective chelating agents to better manage An contamination.

ActiDecorp collaborates with the Technical University of Dresden (TUD), which has advanced radiochemical laboratories and access to facilities at IRE-HZDR for safely handling actinides like Th⁴⁺, U⁴⁺, Np⁴⁺, NpO₂⁺, Pu⁴⁺, Am³⁺, and Cm³⁺. Although U⁴⁺ is not biorelevant, it serves as a model for Np⁴⁺ and Pu⁴⁺ to study the coordination properties along the An(IV) series. The project aims to synthesize and structurally characterize complexes with new ligands. Special care is required to handle U⁴⁺, Np⁴⁺, and Pu⁴⁺ to prevent oxidation. These complexes will be studied using FTIR, XRD, paramagnetic NMR, and EPR spectroscopy. Additionally, X-ray absorption spectroscopy (EXAFS, HR-XAS) at the ROBL beamline in Grenoble will be used to further investigate the coordination sphere of these metal cations.

In solution, TUD will study the interaction of Cm³⁺ with new decorporating agents using time-resolved laser fluorescence spectroscopy (TRLFS), leveraging data from Eu³⁺ and Tb³⁺. This approach allows for determining the stoichiometry and stability constants of solution species at equilibrium. Competition experiments with well-characterized co-ligands like DTPA may also be conducted.

ActiDecorp's multidisciplinary approach involves synthesizing novel high-affinity chelators, characterizing their metal-binding properties, assessing their toxicity, and testing their in vivo efficacy in rodent models. The project seeks to provide a promising and advantageous alternative to current treatments like DTPA, focusing on the superior binding properties of cyclic hydroxamates. This innovative effort aims to develop more efficient and safer treatments for An contamination, addressing critical needs in nuclear safety and medical countermeasures.

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