Pacific Blue Dyes

Pacific Blue, or systemically called 3-carboxy-6,8-difluoro-7-hydroxycoumarin, is a fluorophore used in cell biology. Its maximum excitation wavelength is 401 nm and its maximum emission wavelength is 452 nm. Even at a pH of about 7, its fluorescence is still very high. Pacific Blue is a member of the Pacific Dye Group. Pacific dyes include Pacific Orange, Pacific Green, and Pacific Blue. The maximum absorption of these fluorescent dyes is between 400 and 410 nm, but they have different emission spectra: this allows simultaneous excitation with one laser, which produces maximum emission of 455 nm, 500 nm, and 551 nm, respectively (Note: maximum absorption emission May vary by manufacturer. In flow cytometry, Pacific Blue (and other Pacific dyes) are typically absorbed at 405 nm, and are not allowed with other fluorophores (such as BV421 or V450) that share similar excitation and / or emission spectra use simultaneously.

Pacific Blue Dyes
Figure 1. Chemical structure of Pacific Blue dyes.


In general, Pacific Blue is used as a reactive form for immunohistochemistry or targeted staining and is capable of binding to targeted antibodies. The reaction form used is Pacific Blue succinimide ester or Pacific Blue C5-maleimide.

CD BioScience provides Pacific Blue dyes that can be conjugated to a variety of antibodies, peptides, proteins, tracers and amplification substrates to optimize cell labeling and detection. In addition, reactive dye and protein labeling kits are provided so you can produce your own antibody conjugates or probes.


  1. Lee, Molly M.; et al. Quantification of Small Molecule–Protein Interactions using FRET between Tryptophan and the Pacific Blue Fluorophore. ACS Omega. 2016, 1: 1266–1276.

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