TO-PRO®-3 stain is an excellent far red-fluorescent nuclear and chromosome counterstain that is impermeant to live cells but penetrates compromised membranes characteristic of dead cells, making it a useful indicator of dead cells within a population. The carbocyanine-based dye exhibits far-red fluorescence with excitation at 642 nm and emission at 661 nm. The long-wavelength fluorescence of TO-PRO®-3 stain is well separated from that of commonly used fluorophores imaged in the DAPI and FITC channels.
Long-wavelength light–absorbing dyes such as TO-PRO®-3 stain have the advantage that their fluorescence is usually not obscured by tissue autofluorescence. TO-PRO®-3 stain has very strong binding affinity for dsDNA, with dissociation constants in the micromolar range. It gives strong and selective staining of the nucleus in cultured cells and in paraffin sections.
TO-PRO®-3 stain is among the most sensitive probes for nucleic acid detection, and in addition to cell staining it can be used for staining nucleic acids on solid supports and pre-staining samples for gel or capillary electrophoresis.
TO-PRO®-3 stain dashboard
TO-PRO®-3 stain products
We offer TO-PRO®-3 stain as an iodine salt in DMSO. TO-PRO®-3 stain is also included in the SelectFX® Nuclear Labeling Kit, which provides four spectrally distinct fluorescent dyes for staining nuclei in fixed-cell preparations.
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Fluorescence immunostaining of a fixed co-culture of murine neurons and dendritic cells. Fluorescence immunostaining of a fixed co-culture of murine neurons and dendritic cells. Neurons were labeled with an antibody directed against neurofilament triplet H (NFH) protein and visualized using red-fluorescent tetramethylrhodamine goat anti–mouse IgG.
High-performance nucleic acid stains
We offer a range of nuclear counterstains to provide highly selective nuclear staining with little or no cytoplasmic labeling and a choice of colors for multiplexing with other labels. Additionally, some of the stains can be used in cell-cycle analyses with high-content imaging and flow cytometry.
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FluoCells prepared slide #6 showing a fixed, permeabilized, and labeled muntjac skin fibroblast.
Mitochondria were labeled with mouse anti–OxPhos Complex V inhibitor protein antibody and visualized using orange-fluorescent Alexa Fluor® 555 goat anti–mouse IgG antibody. F-actin was labeled with green-fluorescent Alexa Fluor® 488 phalloidin, and the nucleus was stained with TO-PRO®-3 iodide (pseudocolored magenta).