A catalytic beacon sensor for uranium with parts-per-trillion sensitivity and millionfold selectivity

Liu et al. 10.1073/pnas.0607875104.

Supporting Information

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SI Figure 6
SI Table 1
SI Figure 7
SI Figure 8
SI Figure 9

SI Figure 6

Fig. 6. Sequence alignment obtained for 86 clones from uranium selection. Red indicates 90% sequence conservation, and blue signifies 50% conservation. The locations of the N₅₀ random region and the two conserved regions are indicated. The consensus sequence appears at the bottom.

SI Figure 7

Fig. 7. Quenching of FAM by UO₂²⁺. A 5'-FAM labeled 20-mer DNA (DNA sequence: FAM-5'-ACTCACTATAGGAAGAGATG-3') and its complementary DNA formed a duplex in 300 mM NaNO₃/50 mM Mes, pH 5.5) at 20°C. UO₂²⁺ was titrated into the DNA and FAM fluorescence was presented as a Stern-Volmer plot. In the concentration range used in this paper (<2 mM), quenching of the fluorophore is <2% and therefore can be ignored.

SI Figure 8

Fig. 8. Kinetics of fluorescence change of the sensor in the presence of various metal ions at 10 mM, 200 mM, or 1 mM. All of the experiments were carried out in 50 mM Mes (pH 5.5)/300 mM NaNO₃ at 20°C. The initial rates of fluorescence change (calculated from second 24 to eliminate artifacts associated with metal-induced fluorescence quenching) are plotted in Fig. 3.

SI Figure 9

Fig. 9. (A) Intensity of free fluorescein in the presence of varying concentration of Th(IV). The experiment condition was 50 mM Mes (pH 5.5)/300 mM NaCl at 20°C. The fluorescence intensity was recorded after the system reached equilibrium. The dissociation constant was calculated to be »230 mM. (B) Steady-state fluorescence spectra of free fluorescein (red curve) and fluorescence with 1 mM Th(IV) added (blue curve). The spectra were normalized for comparison.