Astra blue 1%, aqueous is an aqueous solution of astra blue (C.I.: 48048) (CAS No.: 82864-57-1). It is mainly used in histology to visualize cell structures, especially in the staining of nuclei and cell nuclei.

Chemically, Astra Blue belongs to the class of anionic water-soluble dyes with the molecular formula C₅₀H₄₈N₃₉O₃S₃. The dye solution forms double salt bridges upon contact with acidic molecular structures (such as basophils and nucleic acids), resulting in clearly visible staining. This property can be used to identify cells and structures.

Because the chemical reaction between the dye and the structures to be stained is electrostatic, accurate analysis of the color intensity can provide conclusions about the chemical composition and molecular environment of the cell under study. Thus, the application of Astra Blue 1%, aqueous enables differentiated analysis of various cell types and structures in medical diagnostics, histology and scientific laboratories.