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DAPI (4',6-Diamidino-2-Phenylindole, Dihydrochloride) (Invitrogen™)

A popular nuclear and chromosome counterstain, DAPI emits blue fluorescence upon binding to AT regions of DNA. Although the dye is cell impermeant, higher concentrations will enter a live cell.

Hoechst 33258, Pentahydrate (bis-Benzimide), 100 mg (Invitrogen™)

Hoechst 33258 nucleic acid stain is a popular nuclear counterstain that emits blue fluorescence when bound to dsDNA. Its uses are similar to Hoechst 33342 (H-1399) for counterstaining, apoptosis and cell cycle studies, but Hoechst 33258 is reportedly less cell-permeant. This dye is also available in solution (H-3569).

Propidium Iodide ReadyProbes™ Reagent (Invitrogen™)

Propidium iodide is a commonly used dead-cell stain that emits red fluorescence when bound to DNA. Propidium iodide is also used as a counterstain in multicolor fluorescent techniques. With Propidium Iodide ReadyProbes® Reagent, we provide a room temperature-stable solution of classic DNA stain that comes in a convenient-to-use dropper bottle. Just tip and drip two drops per ml to stain your cells.

Features of Propidium Iodide ReadyProbes® Reagent:
• Ready-to-use liquid propidium iodide formulation
• Rapid staining of dead cells without wash steps
• Ready-to-use liquid formulation in convenient dropper bottle—no need to dilute, weigh, or pipette
• Stable at room temperature—keep handy at your work station or cell culture area

Classic Dead Cell Stain
Propidium iodide is a classic fluorescent dye used extensively for staining of dead cells (Figure 1). It exhibits a sufficiently large Stokes shift to allow simultaneous detection of nuclear DNA and FITC or Alexa Fluor® 488-labeled antibodies.

Packaged for Convenience
Propidium Iodide ReadyProbes® Reagent is supplied ready-to-use and can be stored right next to your flow cytometer or in your cell culture lab. A liquid formulation in an ultra-convenient dropper bottle (Figure 2) allows you to stain your cells whenever and wherever they are ready. Just add two drops per ml for optimally bright and distinct nuclear counter-staining.

Multiple Applications
Propidium iodide is membrane-impermeant and excluded from viable cells. It is therefore commonly used for identifying dead cells in a population. Its spectral properties, selectivity for dsDNA, and increased fluorescence when bound to DNA, make propidium iodide ideal for use with green (Alexa Fluor® 488, FITC, GFP) fluorophores in multicolor experiments. Because of its high affinity for DNA, it is also frequently used for counting cells, measuring apoptosis, and sorting cells based on DNA content.

Suggestions for Use
• In most cases, 2 drops/1×106 cells of Propidium Iodide ReadyProbes® Reagent and an incubation time of 15 to 30 minutes will produce bright nuclear staining; however, optimization may be needed for some cell types, conditions, and applications. In such cases, simply add more or fewer drops until the optimal staining intensity is obtained.
• When bound to nucleic acids, the fluorescence excitation maximum for propidium iodide is 535 nm and the emission maximum is 617 nm. Propidium iodide can be excited with a xenon or mercury-arc lamp or with the 488 line of an argon-ion laser. Generally, propidium iodide fluorescence is detected in the FL2 channel of flow cytometers.
• As a preferred red nuclear stain in dead cell analyses using flow cytometry, Propidium Iodide ReadyProbes® Reagent is ideal for use with antibody-based applications.

See other Molecular Probes® imaging tools and reagents.

Hoechst 33342, Trihydrochloride, Trihydrate, 100 mg (Invitrogen™)

Hoechst 33342 nucleic acid stain is a popular cell-permeant nuclear counterstain that emits blue fluorescence when bound to dsDNA. This dye is often used to distinguish condensed pycnotic nuclei in apoptotic cells and for cell cycle studies in combination with BrdU. It is also available in solution (H-3570).

NucGreen™ Dead 488 ReadyProbes™ Reagent (Invitrogen™)

NucGreen® Dead 488 ReadyProbes® Reagent is a cell-impermeant stain that emits exceptionally bright, green fluorescence when bound to DNA. Cells that have lost plasma membrane integrity are stained within minutes, making this an extremely useful stain to estimate live/dead cell ratios and to measure cytotoxicity in kinetic live-cell assays. It is also suitable for staining nuclei in fixed cell preparations and tissue sections.

• Exceptionally bright green fluorescence upon binding to DNA
• Rapid staining of damaged, dead, or fixed cells without wash steps
• Ready-to-use liquid formulation in convenient dropper bottle—no need to dilute, weigh, or pipette
• Stability at room temperature—keep handy at your scope or cell

See other ReadyProbes® reagents for cell staining
See other nuclear stains for imaging

Cell imaging applications
The membrane-impermeable NucGreen® Dead 488 reagent is a high-affinity DNA stain that easily stains cells with compromised cell membranes, yet does not enter living cells. It is therefore ideal for discrimination of live and dead cells. The fluorescence increases more than 500-fold on binding to dsDNA in cells with compromised cell membranes (dying or dead cells), in fixed cells, and tissue slices. The spectral properties, with excitation/emission at 504/523 nm when bound to DNA, are ideal for standard FITC filters. .

Suggestions for use
• NucGreen® Dead 488 reagent may be added directly to cells in full media or buffer solutions
• It easily stains nuclei of fixed cells and tissue slices
• In most cases, 2 drops/ml and an incubation time of 15 to 30 minutes will give bright nuclear staining; however, optimization may be needed for some cell types, conditions, and applications. In such cases, simply add more or fewer drops until the optimal staining intensity is obtained. In most cases, staining intensity increases with time if cells are not washed prior to imaging.
• NucGreen® Dead 488 dye is excited with a maximum at 504 nm when bound to DNA, with an emission maximum at 523 nm. It is detected through standard GFP and FITC filters.

NucRed™ Live 647 ReadyProbes™ Reagent (Invitrogen™)

NucRed® Live 647 ReadyProbes® Reagent is a bright, far-red, cell-permeant nuclear stain for live or fixed cells. It is provided as a room temperature-stable solution in a convenient-to-use dropper bottle. Just add two drops per ml to stain your cells.

• No need to dilute, weigh, or pipette
• Convenient dropper bottle—just use two drops per mL
• Stable at room temperature—keep handy at your scope or cell culture area
• Excited at 638 nm when bound to DNA, with an emission maximum at 686 nm

See other ReadyProbes® reagents for cell staining
See other nuclear stains for imaging

Cell imaging applications
The far-red fluorescence emission makes it ideal for use in combination with blue, green, and red fluorophores, such as Hoechst, GFP/FITC, and Texas Red®.

Suggestions for use
• NucRed® Live 647 ReadyProbes® Reagent may be added directly to cells in full media, or buffer solutions.
• In most cases, 2 drops/mL and an incubation of 15 to 30 minutes will give bright nuclear staining; however, more or fewer drops can be added for optimal staining intensity.
• In most cases, staining intensity increases with time if cells are not washed prior to imaging.
• It is detected through a far-red filter, such as a Cy®5 filter, or a Cy®5 Light Cube for EVOS® imaging systems.

NucBlue™ Live ReadyProbes™ Reagent (Invitrogen™)

Hoechst 33342 is a popular cell-permeant nuclear counterstain that emits blue fluorescence when bound to DNA. With NucBlue® Live ReadyProbes® Reagent we have formulated this classic stain in a room temperature-stable solution that is provided in a convenient-to-use dropper bottle. Just tip and drip two drops per ml to stain your cells.

• No need to dilute, weigh, or pipette
• Convenient dropper bottle—just use two drops per mL
• Stable at room temperature—keep handy at your scope or cell culture area
• Excited by UV light and emits blue fluorescence at 460 nm when bound to DNA nm

See other ReadyProbes® reagents for cell staining
See other nuclear stains for imaging

Cell imaging applications
The spectral properties of Hoechst 33342 (2'-[4-ethoxyphenyl]-5-[4-methyl-1-piperazinyl]-2,5'-bi-1H-benzimidazole), including a large Stokes shift, make it ideal for use with green (Alexa Fluor® 488, FITC, GFP) and red (Alexa Fluor® 594, Texas Red®, rhodamine, mCherry, mKate-2) fluorophores in multicolor experiments. Because of its high affinity to DNA, Hoechst 33342 is also frequently used in cell counting, cell cycle, and cell replication studies to distinguish condensed nuclei in apoptotic cells, for cell-cycle studies in combination with Click-iT® EdU or BrdU staining, as a nuclear segmentation tool in high content imaging analysis, and to sort cells based on their DNA content..

Suggestions for use
NucBlue® Live Cell Stain may be added directly to cells in full media, or buffer solutions.
• In most cases 2 drops/ml and an incubation of 15 to 30 minutes will give bright nuclear staining; however, optimization may be needed for some cell types, conditions, and applications. In such cases simply add more, or fewer, drops until the optimal staining intensity is obtained. In most cases, staining intensity increases with time if cells are not washed prior to imaging.
• NucBlue® Live Cell Stain is excited by UV light at 360 nm when bound to DNA, with an emission maximum at 460 nm. It is detected through a blue/cyan filter, such as a DAPI filter, blue GFP filters, or the Semrock BrightLine® Alexa Fluor® 350 Dye filter set.

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

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.

Hoechst 33258, Pentahydrate (bis-Benzimide) - FluoroPure™ Grade (Invitrogen™)

Because it is manufactured at our ISO 9001—certified facilities in Eugene, Oregon, we can guarantee that FluoroPure Grade Hoechst 33258 is greater than or equal to 98% pure by HPLC.

DAPI (4',6-Diamidino-2-Phenylindole, Dilactate) (Invitrogen™)

DAPI, dilactate is a water-soluble form of the popular nuclear and chromosome counterstain, DAPI. The nuclear stain emits blue fluorescence upon binding to AT regions of DNA. Although the dye is cell impermeant, higher concentrations will enter a living cell.

NucBlue™ Fixed Cell ReadyProbes™ Reagent (Invitrogen™)

DAPI is a commonly used nuclear counterstain for fixed cells that emits blue fluorescence when bound to DNA. With NucBlue® Fixed Cell ReadyProbes® Reagent, we have formulated a high-purity form of this classic stain in a room temperature-stable solution that is provided in a convenient-to-use dropper bottle. Just tip and drip two drops per ml to stain your cells.

• No need to dilute, weigh, or pipette
• Convenient dropper bottle—just use two drops per mL
• Stable at room temperature—keep handy at your scope or cell culture area• DAPI is excited with UV light and detected through a blue/cyan filter

See other ReadyProbes® reagents for cell staining
See other nuclear stains for imaging

Cell imaging applications
DAPI is a classic fluorescent dye used extensively for nuclear staining of fixed cells. In fluorescence microscopy, DAPI is excited with UV light and detected through a blue/cyan filter (Figure 1)..

Suggestions for use
In most cases 2 drops/ml of NucBlue® Fixed Cell Stain and an incubation of 15 to 30 minutes will produce bright nuclear staining; however, optimization may be needed for some cell types, conditions, and applications. In such cases, simply add more, or fewer, drops until the optimal staining intensity is obtained.
• NucBlue® Fixed Cell Stain is excited by UV light at 360 nm when bound to DNA, with an emission maximum at 460 nm. It is detected through a blue/cyan filter, such as a DAPI filter, blue GFP filters, or the Semrock BrightLine® Alexa Fluor® 350 Dye filter set.
• As a preferred blue nuclear stain in fixed cell imaging experiments, NucBlue® Fixed Cell Stain is ideal for use with antibody-based applications.

TO-PRO™-3 Iodide (642/661) - 1 mM Solution in DMSO (Invitrogen™)

TO-PRO®-3 stain is a carbocyanine monomer nucleic acid stain with far-red fluorescence similar to Alexa Fluor® 647 or Cy®5 dyes. 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 TO-PRO®-3 Stain Include:

• Ultrasensitive detection of dsDNA (double-stranded nucleic acids)
• Ideal for flow cytometry and fluorescence microscopy
• Long-wavelength fluorescence well separated from green and red fluorophores
• Excitation⁄Emission: 642⁄661 nm
• Cell impermeant

Many Applications
TO-PRO®-3 and the other monomeric 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, viability detection and counterstaining in multiple-label experiments.

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

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

Expand Your Options for Multicolor Labeling
The long-wavelength fluorescence of TO-PRO®-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 TO-PRO®-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 TO-PRO®-3 spectra and check spectral compatibility with other fluorophores

Hoechst 33342, Trihydrochloride, Trihydrate - FluoroPure™ Grade (Invitrogen™)

Because it is manufactured at our ISO 9001—certified facilities in Eugene, Oregon, we can guarantee that FluoroPure Grade Hoechst 33342 is greater than or equal to 98% pure by HPLC.

NucRed™ Dead 647 ReadyProbes™ Reagent (Invitrogen™)

NucRed® Dead 647 ReadyProbes® Reagent is a cell impermeant stain that emits bright far-red fluorescence when bound to DNA. Since this reagent stains the cells without plasma membrane integrity it is extremely useful to measure viability and to measure cytotoxicity in kinetic live cell assays. NucRed® Dead 647 reagent is also suitable for staining nuclei in fixed cell preparations and tissue sections.

• Exceptionally bright far-red fluorescence upon binding to DNA
• Rapid staining of damaged, dead, or fixed cells without wash steps
• Ready-to-use liquid formulation in convenient dropper bottle
• Stability at room temperature—keep handy at your scope or cell culture area

See other ReadyProbes® reagents for cell staining
See other nuclear stains for imaging

Cell imaging applications
The far-red fluorescence emission makes it ideal for use in combination with blue, green, and red fluorophores, such as Hoechst, GFP/FITC, and Texas Red®.

Suggestions for use
• NucRed® Dead 647 ReadyProbes® Reagent may be added directly to cells in full media, or buffer solutions.
• In most cases, 2 drops/mL and an incubation of 15 to 30 minutes will give bright nuclear staining; however, more or fewer drops can be added for optimal staining intensity.
• In most cases, staining intensity increases with time if cells are not washed prior to imaging.
• It is detected through a far-red filter, such as a Cy®5 filter, or a Cy®5 Light Cube for EVOS® imaging systems.

Hoechst 33342, Trihydrochloride, Trihydrate - 10 mg/mL Solution in Water (Invitrogen™)

Hoechst 33342 nucleic acid stain is a popular cell-permeant nuclear counterstain that emits blue fluorescence when bound to dsDNA. This dye is often used to distinguish condensed pycnotic nuclei in apoptotic cells and for cell-cycle studies in combination with BrdU.