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NucSpot® Nuclear Stains

Cell membrane-impermeant, nuclear-specific counterstains. Suitable for fixed cells or staining dead cells in live cultures.

Product Attributes

Probe cellular localization


For live or fixed cells

For fixed cells

Assay type/options

Live/dead discrimination, Long term staining (24-72h), No-wash staining, Real-time imaging, Tissue staining

Detection method/readout

Fluorescence microscopy, Flow cytometry

Cell permeability

Membrane impermeant

Apoptosis/viability marker

Dead cell stain

Fixation options

Permeabilize before staining, Fix before staining (methanol), Fix before staining (formaldehyde)


Green, Orange, Red, Far-red, Near-infrared

Storage Conditions

Store at 2 to 8 °C

Catalog #
20 uL
100 uL
Clear selection
(Please select quantity above )

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Product Description

NucSpot® Nuclear Stains are cell membrane-impermeant, nuclear-specific counterstains available in a variety of colors from green to near-infrared (near-IR).

  • Nuclear-specific counterstains for fixed cells
  • Selectively stains dead cells in live culture
  • No wash required
  • Color options for FITC, Cy®3, PE, Texas Red®, Cy®5, APC, Cy®5.5, and Cy®7 channels

NucSpot® Stains have minimal fluorescence until they bind to DNA and can be used for no-wash nuclear staining. Unlike other nucleic acid dyes such as propidium iodide (PI), TOTO®, TO-PRO®, and similar dyes that stain both the nucleus and cytoplasm, NucSpot® Nuclear Stains selectively stain the nucleus in fixed and permeabilized cells without the need for RNase treatment. NucSpot® Nuclear Stains also can be used for selective staining of dead cells in unfixed cell cultures for analysis by flow cytometry or fluorescence imaging. Several of the dyes can be continuously incubated with cells for multi-day imaging.

NucSpot® Nuclear Stains

ProductEx/EmDetection ChannelSizeCatalog No.
NucSpot® 500/515497/513 nmFITC*20 uL41040-T
100 uL41040
NucSpot® 555/570559/566 nmCy®3 or PE*20 uL41033-T
100 uL41033
NucSpot® 568/580572/583 nmCy®3 or PE*20 uL41036-T
100 uL41036
NucSpot® 594/615603/613 nmTexas Red® or PE-Texas Red®*20 uL41037-T
100 uL41037
NucSpot® 650/665653/671 nmCy®5 or APC*20 uL41034-T
100 uL41034
NucSpot® 680/700683/707 nmCy®5.5*20 uL41035-T
100 uL41035
NucSpot® 750/780757/780 nmCy®7 or APC-Cy®7*20 uL41038-T
100 uL41038
* May show crosstalk in lower wavelength detection channels. Perform single-stain controls before combining with other probes.
† NucSpot® Far-Red is designed for flow cytometry optical systems and is not recommended for fluorescence microscopy.

Find the Right Dye for Your Application

PFA-fixed, Triton® X-100 permeabilized HeLa cells stained with NucSpot® Nuclear Stains in PBS and imaged by confocal microscopy without a wash step. All stains were used at 1X concentration except for NucSpot® 750/780, which was used at 5X concentration in order to image using 640 nm excitation.

Stain Dead Cells in Live Cultures

Live dead discrimination by flow cytometry using NucSpot® Nuclear Stains. A mixture of untreated and heat-killed Jurkat cells was stained with each NucSpot® Nuclear Stain and analyzed by flow cytometry on a BD CytoFLEX flow cytometerin the detection channel shown on the histogram x-axis. Solid peaks represent stained cells; open gray peaks represent unstained cells. The concentrations of each dye used were: 1X NucSpot® 470, 0.1X NucSpot® 500/515, 0.5X NucSpot® 555/565, 1X NucSpot® 568/580; 0.5X NucSpot® 594/615, 0.05X NucSpot® 650/665, 0.2X NucSpot® 680/700, 0.5X NucSpot® 750/780.

Exceptional Photostability

NucSpot® Nuclear Stains offer improved photostability over commonly used cyanine-based nuclear stains. The figure below shows how NucSpot®  650/665 is significantly more photostable than Thiazole Red Homodimer (TOTO® -3).

Photostability of NucSpot® 650/665 compared to Thiazole Red Homodimer. PFA-fixed, permeabilized HeLa cells were stained with 1X NucSpot® 650/665 or 200 nM Thiazole Red Homodimer (equivalent to TOTO®-3 Iodide). Cells were continuously imaged for 120 seconds by epifluorescence microscopy through a Cy®5 filter set, and images were captured every 10 seconds. Mean fluorescence normalized to time 0 for each image is plotted on the right. NucSpot® 650/665 fluorescence was well-preserved, while Thiazole Red/TOTO®3 fluorescence photobleached rapidly. In addition, NucSpot® 650/665 specifically stained the cell nucleus, while in the absence of RNase-pretreatment, TOTO®-3 stained both cytoplasm and nucleus.

NucSpot® 500/515 is a green fluorescent nuclear stain for the FITC channel. In addition to bright nuclear counterstaining of fixed cells, it can also be used for multi-day live/dead staining of mammalian cells in culture. NucSpot® 500/515  is designed as an improved alternative to NucSpot® 470 which has limited use for cell viability tracking due to its instability in culture medium during long incubation periods.

NucSpot® 555/570 and NucSpot® 568/580 have orange and visible red fluorescence, respectively, and are nuclear-specific alternatives to PI and similar dyes.

NucSpot® 594/615 has deep red fluorescence for the Texas Red® channel.

NucSpot® 650/665 has far-red fluorescence with superior nuclear specificity compared to first-generation far-red nuclear stains such as RedDot™2 and Draq7™.

NucSpot® 680/700 and NucSpot® 750/780 are spectrally unique DNA stains for far-red and near-IR detection.

Biotium also offers NucSpot® Far-Red, a flow cytometry stain developed as an improved alternative to 7-AAD. It shows less bleed-through fluorescence in the PE-Texas Red® channel compared to 7-AAD and is ideal for selective detection of dead cells or DNA content analysis by flow cytometry without RNase treatment.

Learn more about our full selection of Cellular Stains for the nucleus and other organelles.

TOTO and TO-PRO are registered trademarks of Thermo Fisher Scientific; Draq is a trademark of BioStatus Ltd; CY is a registered trademark of Cytiva.

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