Selective Removal and Recovery of Radioactive Cesium Ions Using DNA Aptamer-Based Systems

In this study, we developed a deoxyribonucleic acid (DNA) aptamer-based system for the selective removal and recovery of cesium ions (Cs+). Cs+-binding aptamers were selected using capture-based systematic evolution of ligands by exponential enrichment (capture-SELEX). Among the selected candidates, FA-Cs11 exhibited the highest binding affinity and removal efficiency. FA-Cs11 immobilized on streptavidin-coated agarose beads achieved a maximum removal efficiency of 92.8% for 10 μM Cs+ under the tested conditions. Sequence analysis identified a conserved motif (TATCCAGAGTGACGCAGCA) and G-rich regions in FA-Cs11, which may cotribute to structural features associated with Cs+ recognition. Specificity studies showed preferential removal of Cs+ by FA-Cs11 compared with the tested metal ions, including Co2+, Ni2+, Cu2+, Fe2+, Mn2+, Cr2+, Al3+, and Eu3+. Thermal denaturation enabled the quantitative recovery of Cs+ captured by the FA-Cs11-functionalized beads under the tested conditions. Furthermore, FA-Cs11 exhibited comparable removal performance toward radioactive cesium (137Cs), demonstrating that the aptamer-based system retained its Cs-removal functionality under the short-term radioactive conditions evaluated in this study. Collectively, these findings demonstrate the feasibility of an aptamer-based molecular-recognition system for selective Cs+ separation and recovery and provide a laboratory-scale proof-of-concept for its potential application in radioactive wastewater treatment.