Bio-N⁶-ddATP (Biotin-N⁶-(2’,3’-dideoxy)adenosine-5’ triphosphate) can be used for 3’-end labelling of single-stranded or double-stranded DNA. It is especially useful as a substrate for terminal transferase for the 3’-terminal addition of a single Bio-N⁶-ddAMP. It is also a substrate for Taq DNA Polymerase and other DNA polymerases.

Biotin-labelled oligonucleotides produced by this reaction are suitable as hybridisation probes. Biotin-labelled cDNA produced by this reaction can be used in nucleic acid array assays. Biotin-labelled DNA in hybridisation assays can be detected by a reporter molecule linked to streptavidin, avidin, or and anti-biotin antibody. Such a complex can be detected directly, by the excitation of a fluorophore conjugated to streptavidin, or indirectly by using an enzyme conjugate that can produce an insoluble coloured precipitate.