Recognition of aptamers with different cancer cell lines.

Selectivity study to assess the recognition of selected aptamers to different cell lines including colorectal cancer (DLD-1, HCT 116, HT-29), normal colon (CCD18Co, FHC), leukemia (HL60, NB4, K562, KG-1, CCRF-CEM, Ramos), lung cancer (NCI-H23, H1975, H661, Ludlu), cervical cancer (Hela), ovarian cancer (CAOV3, TOV21G), brain tumor (U87MG) and normal epithelial (HBE 135). A threshold of fluorescence intensity of PE-cy5.5 in the flow cytometry analysis was set such that the control library showed 5% of cells above the threshold. After binding the aptamer signal was evaluated by the percentage of cells above the threshold such that all signals below 10% were considered as background and designated ‘-’. The rest were assigned as follows; 11-30%, +; 31-50%, ++; 51-70%, +++; 71-85%, ++++ and >86, +++++. The final concentration of each aptamer was 250 nM.