Flow cytometry for validating CD62L as a target for aptamer Sgc-3b. (A) Flow cytometry assay of Jurkat E6–1 cells stained with Sgc-3b-FAM and anti-CD62L-PE FAM-labeled random DNA (L45-FAM) and IgG-PE, which do not bind to cells, were used as the negative controls. (B) Flow cytometry results to show the competition of different concentrations of Sgc-3b-FAM with 0.625 μg/ml anti-CD62L-PE in binding toward Jurkat E6–1 cells. (C) Flow cytometry results to show the competition of 5 μg/ml anti-CD62L-PE with 100 nm Sgc-3b-FAM in binding toward Jurkat E6–1 cells. (D) Flow cytometry assay results showed that the siRNA-mediated depletion of CD62L in Jurkat E6–1 cells led to a reduced binding of aptamer Sgc-3b, but not aptamer Sgc-4e. Binding toward anti-CD62L, Sgc-3b and Sgc-4e were assessed at 72 h after siRNA treatment, where reduced binding toward anti-CD62L indicated the successful, albeit modest, knock-down of CD62L after siRNA treatment.