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 impermeantMany ApplicationsTO-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 StainingTO-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 StainingSimultaneous 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 LabelingThe 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.

图2.FluoCells prepared slide #6 showing a fixed, permeabilized, and labeled muntjac skin fibroblast.FluoCells prepared slide #6 (F35925) 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 (Cat. no. A21422). F-actin was labeled with green-fluorescent Alexa Fluor® 488 phalloidin (Cat. no. A12379), and the nucleus was stained with TO-PRO®-3 iodide (Cat. no. T3605, pseudocolored magenta).

图3.Mouse Anti-Alpha Tubulin Monoclonal Antibody (Cat. No. A11126)Microtubules of bovine pulmonary artery endothelial cells that have been labeled with mouse monoclonal anti–a-tubulin antibody (Cat. no. A11126), followed by biotin-XX goat anti–mouse IgG antibody (Cat. no. B2763), and then visualized with Marina Blue® streptavidin (Cat. no. S11221). The cells were next treated with RNase, and the chromosomes were labeled with TO-PRO®-3 iodide (Cat. no. T3605). A series of Z-plane images was acquired with a wide-field optical sectioning confocal laser-scanning microscope. A three-dimensional volume rendering was generated from the deconvolved image series.