Hoechst 33258 analog 3 is widely used in biological research as a fluorescent stain for DNA. It is particularly effective in cell biology for labeling the nuclei of live or fixed cells, enabling visualization under fluorescence microscopy. This compound binds selectively to the minor groove of double-stranded DNA, making it a valuable tool for studying cell cycle dynamics, chromatin structure, and nuclear organization. It is also employed in assays to detect DNA content and ploidy levels in cells, aiding in cancer research and cytogenetic studies. Additionally, its fluorescence properties make it useful in high-throughput screening and flow cytometry applications.