IRDye® 700DX NHS Ester

IRDye 700DX Dye Used for Protein or Nucleic Acid Labeling.

The phthalocyanine dye IRDye 700DX has robust properties that make it suitable for optical imaging when conjugated to antibodies, receptor-binding ligands, small molecules, and more. It is considerably less sensitive to photobleaching than many other organic fluorochromes, and has excellent water solubility and salt tolerance. It can also be an alternative to quantum dots.

IRDye 700DX NHS ester reactive group can be used for labeling primary and secondary amino groups.

Recently, IRDye 700DX has shown potential as a molecular-targeted cancer therapy, or photoimmunotherapy (PIT)1. IRDye 700DX dye-conjugated probes and agents are currently involved in ocular melanoma and head and neck cancer clinical trials.

Which 700 Channel Dye Should I Use?

Dye Structure

IRDye 700DX NHS Ester structure


  • Chemical Formula: C74H96N12Na4O27S6Si3
  • Molecular Weight: 1954.21 g/mol
  • Exact Mass: 1952.37

Absorption and Emission Spectra

Solvent Ext. Coeff. (M-1cm-1) Absorption Maxima Emission Maxima Stokes Shift
Methanol 210,000 680 nm 687 nm 7 nm
Water 165,000 689 nm 700 nm 11 nm
1X PBS 165,000 689 nm 700 nm 11 nm

IRDye 700DX NHS ester is available in labeling kits so that you can label your own compounds for assay or probe development.

Absorption and Emission Spectra in 1X PBS

IRDye 700 DX Absorption and Emission Spectra

IRDye 700DX is Highly Photostable

Photostability was tested by exposure to many sequential rounds of laser imaging. IRDye 700DX remains fluorescent after extended laser exposure. It is more photostable than other 700 nm dyes, including Alexa Fluor® 680, and is substantially more photostable than tetramethylrhodamine (TMR), one of the most photostable fluorescent dyes2.

IRDye® 700DX photostability comparison
Photostability comparison of IRDye 700DX to IRDye 680LT and Alexa Fluor 680. Equimolar amounts of each dye (25 fmol) were spotted onto nitrocellulose membrane. The membrane was scanned repeatedly with the Odyssey® Infrared Imaging System, and signal intensity was normalized to maximum intensity at time = 0.
Photostability of IRDye 700DX, compared to other near-IR fluorescent dyes, and the very photostable TMR dye.
Dye Irradiation intensity (W/cm2) Intensity Gain factor at surface (Gi) Absorption cross section σ01 (λ) (cm2) Excitation rate constant k01 (λ) (excitation/sec) Measured fluorescence decay rate kz (bleached dye/sec) Mean number of survived excitation cycles µ
IRDye 700DX 24.711 2.823 6.200E-16 (680 nm) 1.479E+05 (680 nm) 0.024 >6.161E+6
Alexa Fluor 680 4.961 2.823 5.355E-16 (680 nm) 2.564E+04 (680 nm) 0.535 4.79E+04
Cy5.5 8.790 2.823 7.270E-16 (680 nm) 6.168E+04 (680 nm) >0.454 1.36E+05
Cy7 27.449 2.823 3.440E-16 (780 nm) 1.045E+05 (780 nm) 0.794 1.317E+05
IRDye 800CW 17.475 2.823 9.180E-16 (780 nm) 1.776E+05 (780 nm) 1.730 1.027E+05
TMR 25.073 2.823 2.340E-16 (531 nm) 4.422E+04 (531 nm) 0.191 2.32E+05


  1. M. Mitsunaga, M. Ogawa, N. Kosaka, L.T. Rosenblum, P.L. Choyke, H. Kobayashi, Cancer cell-selective in vivo near infrared photoimmunotherapy targeting specific membrane molecules. Nature Medicine17, 1685-1691, 2011.
  2. X. Peng, D.R. Draney, W.M. Volcheck, G.R. Bashford, D.T. Lamb, D.L. Grone, Y.Zhang, C.M. Johnson, Phthalocyanine dye as an extremely photostable and highly fluorescent near-infrared labeling reagent. Proceedings of SPIE 6097, 2006.

To discuss purchase quantities over 1 gram or commercial development rights using IRDye infrared dyes, please contact Business Development.

Selected P/N: 929-70010,929-70011,829-03700



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