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mFluor™ Blue 580 SE

Fluorescent dye NHS esters (or succinimidyl esters) are the most popular tool for conjugating dyes to a peptide, protein, antibody, amino-modified oligonucleotide, or nucleic acid. NHS esters react readily with the primary amines (R-NH<sub>2</sub>) of proteins, amine-modified oligonucleotides, and other amine-containing molecules. The resulting dye conjugates are quite stable.
Fluorescent dye NHS esters (or succinimidyl esters) are the most popular tool for conjugating dyes to a peptide, protein, antibody, amino-modified oligonucleotide, or nucleic acid. NHS esters react readily with the primary amines (R-NH<sub>2</sub>) of proteins, amine-modified oligonucleotides, and other amine-containing molecules. The resulting dye conjugates are quite stable.
Ordering information
Price ()
Catalog Number1178
Unit Size
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Additional ordering information
InternationalSee distributors
ShippingStandard overnight for United States, inquire for international
Physical properties
Molecular weight832.98
Spectral properties
Absorbance (nm)492
Correction Factor (260 nm)0.363
Correction Factor (280 nm)0.247
Extinction coefficient (cm -1 M -1)400001
Excitation (nm)485
Emission (nm)580
Storage, safety and handling
H-phraseH303, H313, H333
Hazard symbolXN
Intended useResearch Use Only (RUO)
R-phraseR20, R21, R22
StorageFreeze (< -15 °C); Minimize light exposure


Molecular weight
Absorbance (nm)
Correction Factor (260 nm)
Correction Factor (280 nm)
Extinction coefficient (cm -1 M -1)
Excitation (nm)
Emission (nm)
Advances in spectral flow cytometers have expanded applications and capabilities beyond conventional flow cytometry. Now with spectral flow cytometry analysis, researchers and scientists can investigate an increasing number of molecules of interest. However, the potential of spectral flow cytometry is severely limited by the availability of fluorescent labels and readouts. AAT Bioquest's mFluor™ dyes are developed for multicolor flow cytometry-focused applications, in particular, for spectral fluorescence flow cytometry. mFluor™ Blue 580 dye can be well excited with blue laser at 488 nm. It has a huge Stokes shift with emission ~580 nm. mFluor™ Blue 580 dyes are water-soluble, and the protein conjugates prepared with mFluor™ Blue 580 dyes are well excited at 488 nm to give red fluorescence. mFluor™ Blue 580 dye and conjugates are excellent blue laser reagents for flow cytometry detections. Compared to RPE, mFluor™ Blue 580 dyes are much more photostable, making them readily available for fluorescence imaging applications while it is very difficult to use RPE conjugates for fluorescence imaging applications due to the rapid photobleaching of RPE conjugates. It is also a unique fluorochrome for spectral flow cytometry since there are very few existing dyes that have this spectral profile.

Example protocol


Unless otherwise noted, all unused stock solutions should be divided into single-use aliquots and stored at -20 °C after preparation. Avoid repeated freeze-thaw cycles.

1. Protein stock solution (Solution A)
Mix 100 µL of a reaction buffer (e.g., 1 M  sodium carbonate solution or 1 M phosphate buffer with pH ~9.0) with 900 µL of the target protein solution (e.g. antibody, protein concentration >2 mg/mL if possible) to give 1 mL protein labeling stock solution.
Note     The pH of the protein solution (Solution A) should be 8.5 ± 0.5. If the pH of the protein solution is lower than 8.0, adjust the pH to the range of 8.0-9.0 using 1 M  sodium bicarbonate solution or 1 M pH 9.0 phosphate buffer.
Note     The protein should be dissolved in 1X phosphate buffered saline (PBS), pH 7.2-7.4. If the protein is dissolved in Tris or glycine buffer, it must be dialyzed against 1X PBS, pH 7.2-7.4, to remove free amines or ammonium salts (such as ammonium sulfate and ammonium acetate) that are widely used for protein precipitation.
Note     Impure antibodies or antibodies stabilized with bovine serum albumin (BSA) or gelatin will not be labeled well. The presence of sodium azide or thimerosal might also interfere with the conjugation reaction. Sodium azide or thimerosal can be removed by dialysis or spin column for optimal labeling results.
Note     The conjugation efficiency is significantly reduced if the protein concentration is less than 2 mg/mL. For optimal labeling efficiency the final protein concentration range of 2-10 mg/mL is recommended.

2. mFluor™ Blue 580 SE stock solution (Solution B)
Add anhydrous DMSO into the vial of mFluor™ Blue 580 SE to make a 10 mM stock solution. Mix well by pipetting or vortex.
Note     Prepare the dye stock solution (Solution B) before starting the conjugation. Use promptly. Extended storage of the dye stock solution may reduce the dye activity. Solution B can be stored in freezer for two weeks when kept from light and moisture. Avoid freeze-thaw cycles.


This labeling protocol was developed for the conjugate of Goat anti-mouse IgG with mFluor™ Blue 580 SE. You might need further optimization for your particular proteins.
Note     Each protein requires distinct dye/protein ratio, which also depends on the properties of dyes. Over labeling of a protein could detrimentally affects its binding affinity while the protein conjugates of low dye/protein ratio gives reduced sensitivity.

Run conjugation reaction
  1. Use 10:1 molar ratio of Solution B (dye)/Solution A (protein) as the starting point:  Add 5 µL of the dye stock solution (Solution B, assuming the dye stock solution is 10 mM) into the vial of the protein solution (95 µL of Solution A) with effective shaking. The concentration of the protein is ~0.05 mM assuming the protein concentration is 10 mg/mL and the molecular weight of the protein is ~200KD.
    Note     We recommend to use 10:1 molar ratio of Solution B (dye)/Solution A (protein). If it is too less or too high, determine the optimal dye/protein ratio at 5:1, 15:1 and 20:1 respectively.
  2. Continue to rotate or shake the reaction mixture at room temperature for 30-60 minutes. 

Purify the conjugation
The following protocol is an example of dye-protein conjugate purification by using a Sephadex G-25 column.
  1. Prepare Sephadex G-25 column according to the manufacture instruction.
  2. Load the reaction mixture (From "Run conjugation reaction") to the top of the Sephadex G-25 column.
  3. Add PBS (pH 7.2-7.4) as soon as the sample runs just below the top resin surface.
  4. Add more PBS (pH 7.2-7.4) to the desired sample to complete the column purification. Combine the fractions that contain the desired dye-protein conjugate.
    Note     For immediate use, the dye-protein conjugate need be diluted with staining buffer, and aliquoted for multiple uses.
    Note     For longer term storage, dye-protein conjugate solution need be concentrated or freeze dried. 


Common stock solution preparation

Table 1. Volume of DMSO needed to reconstitute specific mass of mFluor™ Blue 580 SE to given concentration. Note that volume is only for preparing stock solution. Refer to sample experimental protocol for appropriate experimental/physiological buffers.

0.1 mg0.5 mg1 mg5 mg10 mg
1 mM120.051 µL600.255 µL1.201 mL6.003 mL12.005 mL
5 mM24.01 µL120.051 µL240.102 µL1.201 mL2.401 mL
10 mM12.005 µL60.025 µL120.051 µL600.255 µL1.201 mL

Molarity calculator

Enter any two values (mass, volume, concentration) to calculate the third.

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Spectral properties

Absorbance (nm)492
Correction Factor (260 nm)0.363
Correction Factor (280 nm)0.247
Extinction coefficient (cm -1 M -1)400001
Excitation (nm)485
Emission (nm)580

Product family

NameExcitation (nm)Emission (nm)Extinction coefficient (cm -1 M -1)Correction Factor (260 nm)Correction Factor (280 nm)
mFluor™ Blue 570 SE55356512000010.2280.179
mFluor™ Blue 630 SE4706344900010.1970.275
mFluor™ Blue 660 SE4816632600010.3380.32
mFluor™ Blue 590 SE5695898100010.6710.406
mFluor™ Blue 620 SE5896169800010.6830.849


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