Azure A (chloride)

Azure A chloride is a phenothiazine dye. Azure A chloride is an alternative DNA dye used for the separation of DNA and protein fragments in agarose gel electrophoresis and PAGE. Azure A chloride can be chemisorbed on the surface of mild steel according to the Langmuir adsorption isotherm to form a protective film. Azure A chloride binds to double-stranded DNA in a non-cooperative manner via weak intercalation, triggering molecular conformational disturbance, restricted rotational motion, and changes in optical activity^[1][2][3]. In Vitro:Azure A chloride (1-100 μM; 1-120 h, 298-328 K) acts as a stable, mixed-type corrosion inhibitor for mild steel in 1.0 M HCl, achieving a maximum inhibition efficiency of 88% at 100 μM after 1 h immersion at 298 K, and maintaining efficiencies above 86% even after 120 h of exposure at the highest concentration^[2].
Azure A chloride inhibits mild steel corrosion via electron donation from nitrogen atoms (N19, N30) and heterocyclic ring carbon atoms (C3, C8) to the metal surface, with enhanced electron-donor activity in aqueous acidic conditions, supporting a chemisorption mechanism^[2].
Azure A chloride (1-60 μM; incubated at 20 ± 0.5-1.0°C) binds to herring testes double-stranded DNA in a non-cooperative, weak intercalative manner with an intrinsic binding constant of ~0.88 × 10⁵ M⁻¹, a binding stoichiometry of ~4.5 base pairs per dye molecule, and induces minor changes to DNA conformation and optical activity in the dye molecule^[3].