Used as a histological stain to detect amyloid deposits in tissue samples. Binds selectively to amyloid fibrils, which appear red under brightfield microscopy. When viewed under polarized light, the stained amyloid shows apple-green birefringence, a key diagnostic feature. Commonly used in pathology for diagnosing amyloidosis in organs like the liver, kidney, and spleen. Also applied in research to study protein aggregation in neurodegenerative diseases.