Fluorescent dyes are widely used for biological detection. They are generally consistent of two moieties, i.e., the fluorophore as Tag, and the functional group either for conjugations or binding to a biological target. For fluorescent labeling dyes, most of fluorescent labeling dyes either target an amino group or thiol group.
Amine-reactive fluorescent probes are widely used to modify peptides, proteins, oligonucleotides, nucleic acids, ligands and other biomolecules. Amine-reactive dyes are most often used to prepare bioconjugates for immunochemistry, fluorescence in situ hybridization (FISH), cell tracing, receptor labeling and fluorescent analog cytochemistry. In these applications, the stability of the chemical bond between the amine-reactive dye and biomolecule is particularly important because the fluorescent conjugates are often subjected to rigorous incubation, hybridization and washing steps. A number of fluorescent amino-reactive dyes have been developed to label various biomolecules, and the resultant conjugates are widely used in biological applications. Three major classes of amine-reactive fluorescent reagents are currently used to label biopolymers: succinimidyl esters (SE), isothiocyanates, and sulfonyl chlorides.