YODi-1 (Oxazole Yellow Homodimer, also known as YOYO®-1) is a green fluorescent carbocyanine dimeric dye. YODi-1 is a cell-impermeant nucleic acid stain that is nonfluorescent in the absence of nucleic acids but exhibits over a thousand-fold fluorescence enhancement upon binding to dsDNA.
The bright fluorescence signal and low background make YODi-1 ideal for staining nucleic acids on microarrays, as well as for nuclear and chromosome counterstaining in multicolor fluorescence labeling experiments. YODi-1 can also be used for the analysis of single molecules of DNA.