Propidium iodide (PI) is a red-fluorescent cell viability dye which is excluded from live cells as it is impermeable to the cell membrane. The dye intercalates DNA and RNA of the dead cells to give red fluorescent signal as it can penetrate dead or damaged cells to give red fluorescent signal. The fluorescence of the PI dye is enhanced 20 to 30 fold upon binding to the nucleic acids and the fluorescence excitation maximum is shifted ~30-40 nm to red and the fluorescence emission is shifted ~15 nm to the blue1.
- Fluorescent dye, membrane-impermeable nucleic acid intercalator
- λex/λem (DNA-bound) = 535/617 m
- λex/ λem (no DNA) = 493/636 nm
- Form: solution, sterile filtered
- Concentration: 1mg/ml in deionized water
- Storage: 4°C; protect from light
- Molecular formula: C27H34I2N4
- Molecular weight: 668.4
- Cas number: 25535-16-4
- Propidium iodide is used widely as a counterstain to differentiate and exclude non-viable cells in flowcytometry analysis.
- It is used in DNA fluorescence imaging to discriminate early and late stages of apoptosis, used to study cell-mediated cytotoxity and for chromosome analysis
- It is used in quantitative DNA analysis
- used as counter stain in fluorescence microscopy