X-ray absorption spectroscopy on uranium ligand exchange in serum between biological ligands and chelating agents

Abstract

Uranium is considered to be a chemical and radiological toxic metal that accumulates in the kidneys and bones after the incorporation. The practical therapy to reduce the health effects by the internal exposure is to treat with decorporation agents such as chelating agents. X-ray absorption spectroscopy (XAS) can provide detailed information about the electronic state and local structure around a specific atom, e.g. bond lengths, coordination number. In the present study, uranium chemical form in serum was analyzed by XAS in the presence and absence of chelating agents to study decorporation effectiveness of human body exposed to uranium. XAS spectra of uranium L3 edge were measured at BL14B1 beamline of SPring-8. Chelating agents used in this study were ethane-1-hydroxy-1,1-bisphosphonic acid and diethylenetriaminepentaacetic acid, respectively. About 150 μL of the serum sample containing uranium and chelating agent was placed in a hole on an acryl cell with 10 mm thickness, and sealed by Kapton poly imide tape. XAS spectra of uranium in serum changed depended on the concentration of the chelating agents, resulting that XAS spectra in the presence of chelating agents were distinguished with those in the absence of the chelating agents. Coordination structure of uranium in serum in the presence of chelating agents was estimated based on the bond distance between uranium and oxygen atom of the ligands.