Figure 1

Mechanism and selection process of aptamer probes. A) Hybridization of aptamer probes with their target molecule involves a structural change (from i to ii), which triggers fluorescent signal restoration due to the increased distance between the fluorophore and the quencher. B) Selection steps within one cycle of cell-SELEX. Briefly, a library of single-stranded sequences is incubated with target cells. Following the washing procedures, negative selection is done to remove sequences that bind non-specifically. Subsequently, the resulting sequences are PCR-amplified before proceeding to the next cycle. Part B is adapted with permission from ref. [38]. Sefah K, Shangguan D, Xiong X, O’Donoghue MB, Tan W: Development of DNA aptamers using Cell-SELEX. Nature protocols 2010, 5:1169–1185. Copyright 2010 by Nature Publishing Group.