Monovalent streptavidin that senses oligonucleotides.

We report a straightforward chemical route to monovalent streptavidin, a valuable reagent for imaging. The one-step process is based on a (tris)biotinylated-oligonucleotide blocking three of streptavidin’s four biotin binding sites. Further, the complex is highly sensitive to single-base differences - whereby perfectly matched oligonucleotides trigger dissociation of the biotin-streptavidin interaction at higher rates than single-base mismatches. Unique properties and ease of synthesis open wide opportunities for practical applications in imaging and biosensing.