High affinity fluorescently tagged aptamer for CD133 (extracellular domaine epitope) (Kd values are 52.3 and 145.1 nM in Hep3B and HT29 cells, respectively). Efficiently internalized upon binding to CD133. Exhibits superior penetration of tumorspheres compared with an antibody to the same target. For optimal binding aptamers require refolding into their tertiary structure prior to use. Please refer to the protocol for information regarding refolding and aptamer use in unfixed cell imaging and flow cytometry. MW (observed): 6847.32.