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Congo red is an organic compound, the sodium salt of 3,3′- ( [1,1′-biphenyl]-4,4′-diyl)bis (4-aminonaphthalene-1-sulfonic acid). It is an azo dye. Congo red is water-soluble, yielding a red colloidal solution; its solubility is greater in organic solvents.
Congo Red is the sodium salt of benzidinediazo-bis-1-naphthylamine-4-sulfonic acid; a diazo dye that is red in alkaline solution and blue in acid solution and used especially as an indicator and as a biological stain.
Used to evaluate the presence and extent of amyloidosis in different organs. Common diseases for Congo red stain include primary amyloidosis, amyloid light chain (AL) seen in plasma cell dyscrasias, amyloid A (AA) associated with inflammatory conditions.
Jan 1, 2019 · Staining with Congo Red (CR) is a qualitative method used for the identification of amyloids in vitro and in tissue sections. However, the drawbacks and artefacts obtained when using this dye can be found both in vitro and in vivo .
Congo red is a reactive agent that changes color from red to dark blue in acidic environments where the pH is less than 3. Acid producing mucosa turns blue within a few minutes, whereas non–acid-producing mucosa remains red.
Congo Red. Congo Red is a linear molecule that is widely used as a staining reagent in the histopathological diagnosis of amyloid fibrils, as it binds with these fibrils and produces a characteristic yellow-green birefringence under polarized light. AI generated definition based on: Carbohydrate Polymers, 2021
Congo red, first of the synthetic dyestuffs of the direct type, that is, not requiring application of a mordant (a substance such as tannin or alum used to fix the colour to cotton fibres). Introduced in 1884, Congo red belongs to a group of azo dyes derived from benzidine.
