Bio-16-ddUTP (Biotin-16-2’,3’-dideoxyuridine-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-16-ddUMP. Biotin-labelled oligonucleotides produced by this reaction are suitable as hybridisation probes and nucleic acid array assays. It is also a substrate for Taq DNA polymerase and other DNA polymerases.

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 using an enzyme conjugate that can produce an insoluble coloured precipitate.