TODi-3 (Thiazole Red Homodimer, also known as TOTO®-3) is a far-red fluorescent carbocyanine dimeric dye. TODi-3 is a cell-impermeant nucleic acid stain that is nonfluorescent in the absence of nucleic acids but exhibits a significant fluorescence enhancement upon binding to dsDNA.
The bright fluorescence signal and low background make TODi-3 ideal for staining nucleic acids on microarrays, as well as for nuclear and chromosome counterstaining in multicolor fluorescence labeling experiments. TODi-3 is non-cytotoxic and may be used for long-term monitoring of cell viability and dead cell detection in culture. The long-wavelength fluorescence of TODi-3 is well separated from green and red fluorophores, which makes it ideal for multicolor fluorescence labeling experiments.
