Widely used in bioconjugation for labeling biomolecules such as antibodies, proteins, and nucleic acids due to its bright red fluorescence and high photostability. Its isothiocyanate group reacts efficiently with primary amines, forming stable thiourea bonds, making it ideal for immunofluorescence, flow cytometry, and fluorescence microscopy. Commonly employed in multicolor staining experiments because of its distinct emission spectrum, allowing clear differentiation from other fluorophores. Also used in biosensors and diagnostic assays where sensitive and specific detection is required.