Hoechst 33342

Hoechst 33342, also known as bisbenzimide, is a blue fluorescent dye with high affinity for double-stranded DNA, especially those with AT-rich sequences. The compound is cell permeable and is often used to stain live eukaryotic and bacterial cells. Hoechst 33342, while closely related to Hoechst 33258, has been observed to exhibit greater cell permeability. Both dyes have an excitation wavelength around 350 nm and an emission wavelength around 461 nm. Hoechst 33342 is often used in flow cytometry and fluorescence microscopy when studying cell viability.