YOYO 1

YOYO-1 is a green fluorescent dye used in DNA staining. It belongs to the family of monomethine cyanine dyes and is a tetracationic homodimer of Oxazole Yellow (abbreviated YO, hence the name YOYO), typically available as tetraiodide salt. In aqueous buffer, free YOYO-1 dye (absorption: λ_max 458 nm, emission: λ_max 564 nm) has very low fluorescence quantum yield, however the intensity of fluorescence increases 3200 times upon binding through bis-intercalation to double-stranded DNA (absorption: λ_max 489 nm, emission: λ_max 509 nm).