CONGO RED INDICATOR FOR MICROSCOPY
Congo red is used for staining in amyloidosis, and for the cell walls of plants and fungi,
and for the outer membrane of Gram-negative bacteria.
Apple-green birefringence of Congo red stained preparations under polarized light is indicative of the presence of amyloid fibrils.
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 an indicator dye that is blue-violet at pH 3.0 and red at pH 5.0.
The mentioned formulation is only one of the ways of preparing the dye solution. Congo Red is the most commonly used dye in Highman and
Puchtler methods. Depending on personal requests and standard laboratory operating procedures, the dye solution can be prepared according to other protocols .
other protocols. The mentioned formulation is only one of the ways of preparing the dye solution. Congo Red is the most commonly used dye in Highman and
Puchtler methods. Depending on personal requests and standard laboratory operating procedures, the dye solution can be prepared according to
other protocols.