Fig. 4.

Selectivity of the catalytic beacon-based UO₂²⁺ sensor. Sensor responses to all competing metal ions at three concentrations (10 μM, 200 μM, and 1 mM) were tested. (Left Inset) The kinetics of fluorescence enhancement in the presence of 1 mM Th(IV) by the sensor (blue curve), a noncleavable control (red curve), and the sensor in the presence of 10 nM UO₂²⁺ (green curve). (Right Inset) Gel-based cleavage assay of the DNAzyme by 10 μM (lane 1), 200 μM (lane 2), 1 mM Th(IV) (lane 3), and 1.7 μM UO₂²⁺ (lane 4). The reaction time was 10 min.