Actinides in Biosystems - Complexation Studies with Relevant Bioligands

Biosystems such as microorganisms, plants, algae’s etc. are influencing for instance the migration of actinides in the environment. It is important to include these processes in the risk assessment of potential high level nuclear waste disposal sites and other affected areas. In general, the overall interaction process of actinides with microbes can be divided into a) direct interaction path ways such as biosorption, bioaccumulation and biotransformation/bioreduction and b) indirect interaction paths such as complexation with released bioligands. The potential of microbes to mobilize actinides by means of the formed bioligands is less investigated.

Our approach is focused on the investigation of selected bioligands having relevant functionalities for a better understanding of the complex actinide interaction processes in biological systems on a molecular level. To achieve this goal a variety of spectroscopic techniques such as time-resolved laser fluorescence spectroscopy (TRLFS) and/or absorption spectroscopy in the ultraviolet-visible-near infrared (UV-vis-NIR) wavelength range will be applied depending on the nature of the actinide element and the bioligand.
This poster gives an overview about our ongoing research in this area by taking three examples: complex formation of curium(III) with adenosine 5’-triphosphate (ATP) [1], curium(III) and amino acids of different functionalities [2], and uranium interactions with molecules containing hydroxamate groups [3].
We want to use this workshop in order to try to answer the question: How can theory help to interpret our experimental results obtained by using spectroscopic methods especially in exploring the structure of the respective aqueous actinide species?

[1] H. Moll, G. Geipel, G. Bernhard, Inorg. Chim. Acta 358 (2005) 2275.
[2] H. Moll, G. Bernhard, Inorg. Chim. Acta (2006) submitted.
[3] M. Glorius, H. Moll, G. Bernhard, manuscript in preparation.

This work was funded by the BMWA under contract number 02E9985.