Lipophilic dye that stains intracellular lipid droplets to produce a bright red fluorescence in live cells.
- Highly useful lipid stain
Nile red is almost nonfluorescent in water but becomes intensely fluorescent, with a strong red emission when in a lipid-rich environment (EX552 nm/EM636 nm). But the fluorescence emission is environmentally sensitive. Intracellular fat vacuoles, filled with neutral lipids such as cholesterol, lipoproteins and triglycerides will fluoresce green (EX 485 nm/EM 525 nm) while polar lipids, such as phospholipids, will fluoresce red. The ratio of green:red fluorescence can be used to normalize cell size and dye uptake and to identify cells that have more "fat vacuoles". The probe can be added directly to the cell culture in order to label the fat vacuoles within adipocytes and these can then be analyzed by flow cytometry. Nile red has also been used to stain lipophilic proteins that have been separated by SDS-PAGE electrophoresis or to detect sphingolipids on thin-layer chromatograms.
