Fig. 1.

Schematic representation of the cell-based aptamer selection. Briefly, the ssDNA pool was incubated with CCRF-CEM cells (target cells). After washing, the bound DNAs were eluted by heating to 95°C. The eluted DNAs were then incubated with Ramos cells (negative cells) for counterselection. After centrifugation, the supernatant was collected and the selected DNA was amplified by PCR. The PCR products were separated into ssDNA for next-round selection or cloned and sequenced for aptamer identification in the last-round selection.