5(6)-Carboxy-eosin, a multifunctional dye, serves as a crucial tool across various scientific, clinical, and industrial applications. In biological experiments, this dye enables researchers to observe and analyze cell structures, track biomolecules, evaluate cell functions, distinguish between cell types, detect biomolecules, study tissue pathology, and monitor microorganisms. Its utility extends beyond basic research to encompass a broad spectrum of diagnostics. Additionally, 5(6)-Carboxy-eosin finds extensive use in traditional sectors like textile dyeing and in innovative areas such as functional textile processing, food pigments, and dye-sensitized solar cells.