Biotin-labelled oligonucleotides can be used to link the oligonucleotide to streptavidin-protein conjugates, streptavidin affinity columns, or labelled streptavidin. Attachment of a biotin molecule to the 3’ terminus can also be used to prevent 3’ exonuclease digestion and 3’ extension during amplification reactions
Biotin-TEG contains a 16-atom mixed polarity spacer based on a triethylene glycol containing 4 oxygen atoms. These O-atoms confer some hydrophilic properties to the arm. This biotin phosphoramidite can be branched allowing the introduction of multiple biotins both at the 5’ or 3’ ends of the oligonucleotide. The 16-atom spacer of Biotin-TEG provides the biotin with good accessibility towards the streptavidin. In addition, the presence of a few O-atoms within the arm renders it more linear in comparison to other more hydrophobic arms when used in aqueous buffers for hybridization experiments.