Try our bright and photo bleach-resistant Deep Red Nucleic Acid Stain for fixed or dead cells.

TOTO™-3 Iodide (642/660) - 1 mM Solution in DMSO

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TOTO®-3 stain is a carbocyanine dimer with far-red fluorescence similar to Alexa Fluor® 647 or Cy® 5 dyes that is easily distinguished from fluorescein and rhodamine. It is useful as a nuclear counterstain and dead cell indicator, and is among the highest-sensitivity probes for nucleic acid detection.

Important Features of TOTO®-3 Include:

• Nonfluorescent in the absence of nucleic acids
• Very bright fluorescence signal
• Ideal for flow cytometry and fluorescence microscopy
• Long-wavelength fluorescence is well separated from green and red fluorophores
• Cell-impermeant
• Excitation⁄Emission: 640⁄660 nm

Many Applications
TOTO®-3 stain and the other dimeric cyanine stains have wide applicability due to their low background and bright fluorescence. Uses include staining of nucleic acids on solid supports, prestaining of samples for gel or capillary electrophoresis, and nuclear counterstaining in multiple-label experiments. Electrophoresis of samples prestained with TOTO®-3 or other dimeric cyanine dyes is possible due to the unusual stability of the dye-Nucleic Acid complexes.

TOTO®-3 Stain has High Selectivity for Nuclear Over Cytoplasmic Staining
TOTO®-3 stain gives strong and selective nuclear staining in cultured cells and in paraffin sections. TOTO®-3 stain and other carbocyanine dimers have very strong binding affinity for dsDNA, with dissociation constants in the micromolar range.

Use TOTO®-3 Stain for 2-Color Viability Staining
Simultaneous labeling with a green-fluorescent SYTO® dye and cell-impermeant TOTO®-3 or TO-PRO®-3 stains are frequently used to assess cell viability. TOTO®-3 and TO-PRO®-3 stains both have much greater extinction coefficients than that of DNA-bound propidium iodide.

Extend Your Possibilities for Multicolor Labeling
The long-wavelength fluorescence of TOTO®-3 stain is well separated from that of commonly used fluorophores, such as our popular Alexa Fluor® dyes, Oregon Green, ® fluorescein (FITC), rhodamine (TRITC), Texas Red, coumarin (AMCA), Marina Blue™ and Pacific Blue™ dyes. Additionally, long-wavelength light–absorbing dyes such as TOTO®-3 stain have the advantage that their fluorescence is usually not obscured by the autofluorescence of tissues.
Explore other probes for the nucleus

Learn more about nucleic acid detection on gels, blots, and arrays.

Read more about cyanine dyes and other nucleic acid stains.

Find out more about viability and cytotoxicity assay reagents.

Plot the TOTO®-3 spectra and check spectral compatibility with other fluorophores

For Research Use Only. Not intended for any animal or human therapeutic or diagnostic use.
For Research Use Only. Not for use in diagnostic procedures.


Color: Red
For Use With (Equipment): Fluorescence Microscope
Cell Permeability: Cell-Impermeant
Sub-Cellular Localization: Nucleic Acids, Nucleus
Detection Method: Fluorescent
Excitation⁄Emission (nm): 642⁄660
Product Line: TOTO®
Product Size: 200 µL
Shipping Condition: Room Temperature

Contents & storage

Store in freezer (-5 to -30°C) and protect from light.


Manuals & protocols