Himedia Propidium iodide

Propidium iodide (PI) is a nucleic acid binding dye that intercalates into the major groove of double stranded DNA as well as RNA with very low base-preference and produces red fluorescence. Since PI also binds double stranded RNA, it is necessary to treat the cells with RNases for optimal DNA resolution. PI cannot cross an intact cell membrane but can cross membrane of damaged cells and stains intracellular nucleic acids and can be used for determining cell viability. In dual staining with Acridine orange, PI excludes Acridine orange competitively from the nuclei of damaged cells and makes it possible to distinguish and count all live and dead cells.