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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.
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 .
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.
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.
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.
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. From: Carbohydrate Polymers, 2021
Jan 9, 2022 · Definition. Staining with Congo Red (CR) is a qualitative method used for the identification of amyloids in vitro and in tissue sections. Principle. The Congo red staining principle is based on the formation of hydrogen bridge bonds with the carbohydrate component of the substrate.
Feb 26, 2020 · Congo Red is still used for that purpose today, actually, even though we have numerous other techniques to distinguish proteins in tissue samples. But what's been unclear is how it actually binds to the amyloid fibrils.
Sep 8, 2014 · “Congo red” is not the name of a famous African explorer, but a dye that dates to 1883. It was synthesized by P. Böttiger as a textile dye, but it subsequently became more important as a pH indicator. It colors aqueous solutions blue below pH 3.0 and becomes red above pH 5.0.
