Figure 1

Aptamer recognition of cultured NB4 and HL60 leukemic cells. (a). Comparison of aptamer recognition of cultured NB4 and HL60 leukemic cells. Individually synthesized biotin-labelled aptamers and PE-streptavidin were analyzed with flow cytometry in order to compare their ability to recognize NB4 and HL60 cells. Single-stranded library DNA was used as a negative control. The binding of selected aptamers with cells is illustrated as the following: negative control (black); JH6 (green); JH19 (blue); K19 (red). The final concentration of these aptamers in binding buffer was 150 nM. (b). Determination of the aptamer binding affinities to NB4 cells. The biotin-labeled aptamers and PE-labeled streptavidin were used for the binding assays. The background binding was measured by using unselected single-stranded library DNA. The fluorescence intensity geometric means of bound aptamers was determined by flow cytometry. The equilibrium dissociation constants (Kd) of the fluorescent ligands were obtained by fitting the dependence of specific binding fluorescence intensity on the concentration of the ligands to the Equation Y = Bmax*X/(Kd + X) using the GraphPad Software (San Diego, CA, USA) as described in previous studies [13].