Hoechst 33342 amine is an excellent building block for developing site-specific nucleic acid probes. It can be readily conjugated to carbonyl-containing biomolecules (such as antibodies, peptides and oligos). Hoechst 33342 is a DNA-specific dye that binds to the minor groove of double-stranded DNA. It emits blue fluorescence when bound to DNA. Its excitation maximum is around 350 nm, and the emission maximum is approximately 460 nm. Its ability to readily penetrate live cell membranes makes it suitable for staining live cells. This property allows researchers to monitor nuclear morphology and DNA content in living cells. Hoechst 33342 is commonly used in fluorescence microscopy to visualize the nucleus of cells.