The LRSI lab is part of the Health and Expertise Division of the ASNR, which develops analytical methods in radiochemistry and conducts research on the speciation and biodistribution of radionuclides from the cellular to the organism level, and then develops medical countermeasures in case of contamination.

Research project “In vitro study of the chelation of radionuclides by a functionalized polymer: application to oral decorporation”

For decades, many actinides (uranium, plutonium, americium, etc.) and other radioisotopes such as cesium, cobalt, strontium or polonium have been used in various applications (civil, industrial, and military). In the event of internal human exposure, the long-term health effects are numerous (cancer, necrosis, hematological disorders, etc.). To prevent organ damage, it is necessary to have an effective medical countermeasure. However, the currently recommended treatment (DTPA = diethylenetriamine pentaacetic acid) is ineffective and no specific treatment exists after oral contamination to prevent the gastro-intestinal absorption of the forementioned radionuclides. Recently, chemists from the university of Lyon-Claude Bernard and industrial partners have synthesized a grafted chitosan based-polymer with the metal cation chelating group DOTAGA. This functionalized polymer named MEX-CD1 proved to efficiently complex and to prevent the intestinal absorption of metal cations such as cadmium or lead after oral exposure

This postdoctoral position is part of the I-DECoRP research program, co-funded by I-Démo (France 2030 plan), which aims to evaluate the decorporation potential of the functionalized polymer MEX-CD1 to improve management in cases of internal contamination by various radionuclides and thus prevent their deposition in the main target organs (liver, kidneys, bones).

Under the supervision of research engineers, the candidate will also work closely with the laboratory's researchers, engineers, and technicians. The candidate will be responsible for conducting in vitro studies to assess the chemical affinity between the radionuclides of interest (uranium, plutonium, thorium, americium, neptunium, cesium, cobalt, strontium, and polonium) and the functionalized polymer MEX-CD1.

This project is led by the company MexBrain and has six partners on board: Nano-H, three laboratories from University Lyon 1 (ILM, IMP, LAGEPP), Institut Gustave Roussy (IGP) and ASNR.

Mission

The position holder will carry out these in vitro chelation studies on synthetic media mimicking different compartments of the gastrointestinal tract (stomach, small intestine, colon) by varying the pH (2; 4.5 and 8), in the presence or absence of cations (mimicking the alimentary bolus) that can interfere with the chelation of the target isotopes and under thermostated conditions (37°C), to get as close as possible to physiological conditions. The principle of the tests is based on the evaluation of the chelation rate of the isotopes as a function of the quantity of polymer by the mean of ultrafiltration experiments: after an incubation period of MEX-CD1 with the isotopes, the mixture is ultrafiltered through a semi-permeable membrane. Depending on the nature of the radiation and the activities used, the analysis of the isotopes in the different fractions (filtrate and concentrate) will be carried out by inductively coupled plasma mass spectrometry (ICP-MS), alpha or gamma spectrometry.

This includes, but is not limited to:

• Performing in vitro chelation studies of the radioisotopes (uranium, plutonium, thorium, americium, neptunium, and polonium)  or stable isotopes (cesium, cobalt and strontium) by the functionalized polymer MEX-CD1 using the ultrafiltration technique;
• Analyzing the radionuclides and metal ions in the different mediums and samples using analytical techniques (ICP-MS, alpha or gamma spectrometry);
• Analyzing the results of experiments and writing articles for publication in peer-reviewed journals, as well as research reports for internal or external purpose;
• Preparing and presenting talks and poster presentations at internal and external seminars and meetings when requested and approved;

The postdoctoral fellow shall have:

• PhD degree in physical chemistry, coordination chemistry, biology, chemistry or a relevant discipline from a recognized university;
• Comprehensive background and experience in one or more of the following areas: metal complexation and chelation, coordination chemistry, analytical chemistry, biochemistry or radiochemistry;
• Demonstrated ability to publish research results as a lead author in peer-reviewed scientific literature
• Effective communication skills to present results of research as demonstrated by a record of conference or other oral presentations in English
• Demonstrated high organisation skills, interpersonal skills and ability to work as a part of a multidisciplinary and dynamic team

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