3-Methyl-2-([1-[3-(trimethylammonio)propyl]-4(1H)-quinolinylidene]methyl)-1,3-benzothiazol-3-ium diiodide

TO-TAP-1 (Thiazole Orange Monomer, also known as TO-PRO^®-1) is a green fluorescent carbocyanine monomeric dye. TO-TAP-1 is a cell-impermeant nucleic acid stain that is nonfluorescent in the absence of nucleic acids but exhibits a multiple fluorescence enhancement upon binding to dsDNA.

The bright fluorescence signal and low background make TO-TAP-1 ideal for staining nucleic acids on microarrays, as well as for nuclear and chromosome counterstaining in multicolor fluorescence labeling experiments. TO-TAP-1 is non-cytotoxic and may be used for long-term monitoring of cell viability and dead cell detection in culture.