5-Ethynyl-2'-deoxyuridine (5-EdU)

5-EdU (5-Ethynyl-2'-deoxyuridine) can be used as a replacement for BrdU (5-Bromo-2'-deoxyuridine) to measure de novo DNA synthesis during the S-phase of the cell cycle. 5-EdU is cell permeable and incorporates into replicating DNA instead of its natural analog thymidine. The resulting ethynyl-functionalized DNA can subsequently be detected via Cu(I)-catalyzed click chemistry that offers the choice to introduce a Biotin group (via Azides of Biotin) for subsequent purification tasks or a fluorescent group (via Azides of fluorescent dyes) for subsequent microscopic imaging [1-5].