RNA and DNA aptamers in cytomics analysis.

Using systematic evolution of ligands by exponential enrichment (SELEX), RNA or DNA molecules are selected from a combinatorial oligonucleotide library by their ability to bind their targets, i.e., cell surface antigens, with affinity and specificity similar to that of monoclonal antibodies. The generation of these high-affinity binders, also denominated aptamers, is carried out in vitro and does not involve animals. Therefore, aptamers can be developed against almost every molecule of biological importance, including toxins and nonimmunogenic targets, against which antibodies cannot be raised. The incorporation of modified pyrimidines resulting in nuclease-resistant RNA aptamers makes them promising candidates for studying protein interactions in vitro and in vivo. DNA aptamers do not need modifications for most applications. The protocols in this unit can be used for the development of fluorescent-tagged RNA or DNA aptamers for any cell surface protein in cytomics analysis.