Congo red

Congo red is a synthetic dye that is used in the laboratory primarily for the staining of cellulose in plant tissues. It is also used in the Amyloid staining, as it binds to amyloid protein in tissues and shows apple-green birefringence under polarized light.

History

Congo red was first synthesized in 1883 by Paul Böttiger, a German chemist, who was working for the AGFA Corporation at the time. He named it "Congo red" in reference to the recent colonization of the Congo in Africa.

Properties

Congo red is an azo dye. Azo dyes are compounds where two hydrocarbon groups are joined by two nitrogen atoms. The dye has a strong affinity for cellulose fibers and is used in the textile industry for dyeing cotton.

Uses

Congo red is used in biology and pathology for the staining of cellulose and amyloid fibers. In the Congo red test, the dye is used to identify the presence of amyloid fibers in tissues. The dye binds to the fibers and under polarized light, they show apple-green birefringence.

Health effects

Exposure to Congo red can cause irritation to the skin, eyes, and respiratory tract. It may also cause effects on the blood, resulting in hemolysis (destruction of red blood cells).

See also

• Azo dye
• Amyloid
• Congo red test
• Cellulose

References

• 
  Congo red 2D skeletal structure
• 
  Cardiac amyloidosis under very high magnification