Oil Red O Staining Solution

Oil Red O is a lipid-soluble azo dye. When lipids in a sample (such as lipid droplets and triglycerides) come into contact with Oil Red O, the dye molecules diffuse physically into the lipids and form noncovalent interactions with them, causing the lipids to appear bright red. Oil Red O shows selectivity in binding to lipids, with a strong affinity for neutral fats but weaker binding to polar lipids such as phospholipids. Therefore, it stains lipid droplets but not biological membranes.