Widely used in cell biology and flow cytometry, this chemical serves as a fluorescent stain for DNA. It is commonly applied to assess cell viability because it cannot penetrate intact cell membranes—thus staining only dead or membrane-damaged cells. This property makes it ideal for distinguishing live from dead cells in a population. It is frequently used in fluorescence microscopy to visualize nuclear morphology and identify apoptotic cells, which show fragmented DNA. In flow cytometry, it helps determine cell cycle phases by measuring DNA content in fixed or permeabilized cells. Additionally, it is employed in microbial studies to evaluate membrane integrity in bacteria and yeast. Due to its strong DNA binding, it is also used in gel electrophoresis to detect nucleic acids, serving as an alternative to ethidium bromide.