Picrosirius Red Staining

Picrosirius red (acid red 80) is a direct dye for collagen that binds specifically to the triple helix structure of fibrillar collagens and allows direct visualization and quantification under light and polarized light microscopy. Introduced by Junqueira and colleagues in 1978, picrosirius red staining has become the gold standard for assessing collagen deposition and organization in tissue sections, scaffolds, and cell cultures. The key advantage is that picrosirius red-stained collagen exhibits birefringence under polarized light, enabling researchers to visualize not only the amount of collagen but also its degree of organization and fibril maturity—information crucial for evaluating bone, cartilage, skin, and tendon engineering.