5-Maleimido-eosin is a versatile dye used extensively in biological experiments. Dyes play a crucial role in enabling researchers to observe and analyze cell structures, track biomolecules, evaluate cell functions, differentiate cell types, detect biomolecules, assess tissue pathology, and monitor microorganisms. Their applications extend from fundamental scientific research to a wide range of clinical diagnostics. Additionally, dyes are prevalent in traditional uses like textile dyeing and in emerging areas such as functional textile processing, food pigments, and dye-sensitized solar cells.