Propidium iodide (PI)

A membrane-impermeant nucleic acid intercalator. The dye is commonly used to selectively stain dead cells in a cell population and also used as a counterstain in multicolour fluorescent imaging. • Ex/ Em (DNA-bound) = 535/617 nm • Ex/ Em (no DNA) = 493/636 nm • Orange red solid soluble in H 2 O or DMSO • Store at 4°C and protect from light, especially in solution • C27H34I2N4 • MW: 668.4 • [25535-16-4]