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The "Sigma plan" https://www.sigmaplan.be/en/ aims to create in Belgium inundation zones along the Grote Nete river to prevent Antwerp from flooding in extreme weather conditions. The riverbanks of the Grote Nete are at some hotspots historically contaminated by the phosphate industry resulting in Naturally Occurring Radionuclides (NOR) legacy. 226Ra is from a radiation protection point of view one of the most important radionuclides present at the hot spot under study, with a local soil activity concentration higher than 3000 Bq/kg 226Ra. In this paper, we identify the most relevant mechanisms governing the mobility of 226Ra. We selected for this study the role of CaSO4.2H2O, clay minerals and humic acids as the main contributors determining the speciation of Ra, due to their presence at the hot spot, their cation exchange capacity and their functional group density, respectively. Various novel analytical chemistry approaches were developed to study the prevailing reaction mechanisms that impact the solid-liquid distribution of 226Ra. We show that 226Ra coprecipitates in a (Ca,Ra)SO4 solid solution due to the high Ca2+ and SO42- concentrations in the local hot spot. If CaSO4.2H2O is not saturated in the soil solution, 226Ra adsorption to clay minerals counteracts the tendency of 226Ra partitioning to the liquid phase by interactions with humic and fulvic acids. Interactions between different soil compounds may further alter the partitioning of Ra. As, Cd, Pb and Zn in the hot spot are significantly above background values in Flemish sediments. Pb may be coprecipitated as sulphate salts, whereas Cd and Zn are most probably partially present as arsenate salts. The excess of Zn may interact with humic acids. The observed reaction mechanisms suggest that Ca2+ might play a key role in the immobilisation of Ra. The role of Ca2+ as immobilisation agent of the other contaminants is discussed.

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During the last decade there has been remarkable integration of radiation protection research in Europe, driven by six research platforms. The platforms are associations of research centres, university research groups and funding bodies in Member States that are dedicated to specialised areas of research in radiation protection, such as health risks (MELODI), radioecology (ALLIANCE), radiological emergencies (NERIS), dosimetry (EURADOS), medical use of radiation (EURAMED) and societal aspects (SHARE). Recently these platforms established an umbrella organisation MEENAS, to endorse further integration and joint activities in research, education and training, and infrastructures. A milestone in this process of integration and priority setting was achieved in 2020 when the first edition of the joint roadmap for radiation protection research was finalised. In this paper we describe the various roles for research and development in the radiation protection context, ranging from basic scientific knowledge underpinning the system of protection to research supporting the development and application of international standards and research and development activities needed to ensure safety in radiation practices and in potential exposure scenarios. We describe the process of how the joint roadmap has been developed and how it could be implemented. Finally, we address the need to anticipate potential future exposure scenarios and to systematically consider the impact of emerging technologies and global challenges in the context of radiation protection. The joint roadmap is a living document that needs to be regularly updated to cover both current and potential exposures of humans and the environment.

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Aptamers provide a potential source of alternative targeting molecules for existing antibody diagnostics and therapeutics. In this work, we selected novel DNA aptamers targeting the HER2 receptor by an adherent whole-cell SELEX approach. Individual aptamers were identified by next generation sequencing and bioinformatics analysis. Two aptamers, HeA2_1 and HeA2_3, were shown to bind the HER2 protein with affinities in the nanomolar range. In addition, both aptamers were able to bind with high specificity to HER2-overexpressing cells and HER2-positive tumor tissue samples. Furthermore, we demonstrated that aptamer HeA2_3 is being internalized into cancer cells and has an inhibitory effect on cancer cell growth and viability. In the end, we selected novel DNA aptamers with great potential for the diagnosis and possible treatment of HER2-positive cancer.

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One of the most essential aspects to the success of radiopharmaceuticals is an easy and reliable radiolabelling protocol to obtain pure and stable products. In this study, we optimized the bioconjugation and gallium-68 ((68) Ga) radiolabelling conditions for a single-stranded 40-mer DNA oligonucleotide, in order to obtain highly pure and stable radiolabelled oligonucleotides. Quantitative bioconjugation was obtained for a disulfide-functionalized oligonucleotide conjugated to the macrocylic bifunctional chelator MMA-NOTA (maleimido-mono-amide (1,4,7-triazanonane-1,4,7-triyl)triacetic acid). Next, this NOTA-oligonucleotide bioconjugate was radiolabelled at room temperature with purified and pre-concentrated (68) Ga with quantitative levels of radioactive incorporation and high radiochemical and chemical purity. In addition, high chelate stability was observed in physiological-like conditions (37 °C, PBS and serum), in the presence of a transchelator (EDTA) and transferrin. A specific activity of 51.1 MBq/nmol was reached using a 1470-fold molar excess bioconjugate over (68) Ga. This study presents a fast, straightforward and reliable protocol for the preparation of (68) Ga-radiolabelled DNA oligonucleotides under mild reaction conditions and without the use of organic solvents. The methodology herein developed will be applied to the preparation of oligonucleotidic sequences (aptamers) targeting the human epidermal growth factor receptor 2 (HER2) for cancer imaging.

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