4-Carboxy-pennsylvania green, a versatile dye, serves as a critical tool in various biological experiments. Its uses extend to observing and analyzing cell structures, tracking biomolecules, evaluating cell functions, distinguishing cell types, detecting biomolecules, studying tissue pathology, and monitoring microorganisms. The applications of this dye span from basic scientific research to a broad spectrum of clinical diagnostics. Additionally, it is extensively employed in traditional industries like textile dyeing and emerging sectors including functional textile processing, food pigments, and dye-sensitized solar cells.