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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 a direct diazo dye used for staining amyloid in tissue sections (Biosci Rep 2019;39:BSR20181415) This organic compound forms complexes with the misfolded proteins deposited in amyloidosis; analysis of the emission spectra from these complexes reveals the optical reactivity under polarized light, described as apple green ...
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 is synthesised by coupling bis-diazotised benzidine with two molecules of napthionic acid. The blue dye so obtained is converted into its red disodium salt during its salting out with sodium chloride ( Fig. 4.2 ).
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 benzidine-based anionic diazo dye. It is a histological dye which binds to many amyloid proteins and is used for the quantification of amyloid β-peptide aggregation. [5] Congo red also interacts with β-D-glucans, polysaccharides containing continuous β-(1→4)-linked D-glucopyranosyl units and some hemicellulosic ...
Nov 1, 2022 · Congo red dye (CR) continues to be a persistent pollutant of environmental concern. CR is one of the 80% of industrially used and discharged dyes, ultimately producing toxic nature to water. Owing to simplicity and low-cost, adsorption technology is preferred for CR removal.
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.
Jan 1, 2019 · Staining with Congo Red dye (CR) is one of the major methods used to detect the amyloid structure of protein aggregates. However, a series of experiments have shown that CR staining is insufficient for confirmation of the amyloid nature of protein aggregates. This review details the history of amyloid research using CR dye.
Feb 26, 2020 · So there was a tremendous amount of sheer experimentation, and in 1922 Bennhold found that the dye Congo Red (CR) was particularly good for amyloid deposits in pathology samples. Congo Red had been around since the 1880s, and is a story by itself.
