NucView® 405 Caspase-3 Substrate, 1 mM in PBS, provides a convenient tool for detecting apoptosis in intact cells based on caspase-3/7 activity using either confocal microscopy or flow cytometry. In contrast to other fluorogenic caspase substrates or fluorescent caspase inhibitor based (FLICA) assays, NucView® caspase-3 substrates can be used to detect caspase-3/7 activity within individual intact cells without inhibiting apoptosis progression. NucView® substrates consist of a fluorogenic DNA dye coupled to the caspase-3/7 DEVD recognition sequence. The substrate, which is initially non-fluorescent, penetrates the plasma membrane and enters the cytoplasm. In apoptotic cells, caspase-3/7 cleaves the substrate, releasing the high-affinity DNA dye, which migrates to the cell nucleus and stains DNA with fluorescence. Thus, NucView caspase-3 substrates are bifunctional, allowing detection of caspase-3/7 activity and visualization of morphological changes in the nucleus during apoptosis. The staining is also formaldehyde-fixable. NucView® 405 dye is excited by the 405 nm laser line for detection by confocal microscopy in the DAPI channel, or by flow cytometry in the Pacific Blue® channel. NucView® 405 is ideal for caspase-3 detection in multi-color applications for researchers who wish to reserve the green fluorescence channel for other detection reagents. Note: NucView® 405 signal may be difficult to observe using epifluorescence microscopy. Confocal microscopy using 405 nm laser excitation is recommended for imaging. NucView® 405 Caspase-3 Substrate also is offered as a 1 mM solution in DMSO. The substrate in PBS is formulated for use in cells that are sensitive to DMSO toxicity. In non-DMSO sensitive cell types, adding DMSO during the substrate incubation may enhance NucView® 405 staining. Biotium also offers green fluorescent NucView® 488 caspase-3 substrate and kits, as well as orange fluorescent NucView® 530. Pacific Blue is a registered trademark of Thermo Fisher Scientific.