Fig. 3.

Binding Affinity and Specificity of aptamer sequences. A) K_D determination. The dissociation constants for aptamers C7 (K_D = 89.41 ± 18 nM) (black dots) and C9 (K_D = 231.9 ± 15 nM) (black triangles) were calculated fitting the bound fraction curves from slot blot assays to a one binding site non-linear regression model (C7 R² = 0.83; C9 R² = 0.92). B) Binding specificity of C7 (left panel) and C9 (right panel) aptamers. Radiolabeled aptamer DNA (15 pM) was incubated with 600 nM of purified S protein. BSA (600 nM) and no protein negative controls were included. The data was analyzed using one-way ANOVA with post hoc Tukey's multiple comparisons test (99% CI). Asterisks indicate statistical significance (n = 3, p < 0.0001). For both aptamers no statistically significant differences were found between BSA and without protein (C7: p > 0.039; C9: p > 0.99).