Alizarin Red Staining

Alizarin red-S (1,2-dihydroxyanthraquinone-3-sulfonic acid) is a calcium-binding dye that forms a colored complex with mineralized deposits, enabling direct visualization and quantification of bone matrix mineralization. Developed as a standard assay by Gregory and colleagues in 2004, alizarin red staining is widely used to evaluate osteogenic differentiation of stem cells, assess the mineralization-promoting effects of biomaterial scaffolds and growth factors, and measure the calcium content of bone tissue and engineered constructs. The assay is rapid, quantitative, and provides both visual and colorimetric readout.