Fluorophore

A fluorophore (or fluorochrome, similarly to a chromophore) is a fluorescent chemical compound that can re-emit light upon light excitation. Fluorophores typically contain several combined aromatic groups, or plane or cyclic molecules with several π bonds.

Fluorophores are sometimes used alone, as a tracer in fluids, as a dye for staining of certain structures, as a substrate of enzymes, or as a probe or indicator (when its fluorescence is affected by environment such as polarity, ions,...). But more generally it is covalently bonded to a macromolecule, serving as a marker (or dye, or tag, or reporter) for affine or bioactive reagents (antibodies, peptides, nucleic acids). Fluorophores are notably used to stain tissues, cells, or materials in a variety of analytical methods, i.e. fluorescent imaging and spectroscopy.

Fluorescein, by its amine reactive isothiocyanate derivative FITC, has been one of the most popularized fluorophores. From antibody labeling, the applications have spread to nucleic acids thanks to (FAM(Carboxyfluorescein), TET,...). Other historically common fluorophores are derivatives of rhodamine (TRITC), coumarin, and cyanine. Newer generations of fluorophores, many of which are proprietary, often perform better (more photostable, brighter, and/or less pH-sensitive) than traditional dyes with comparable excitation and emission.