A BODIPY-Hoechst conjugate for nuclear DNA staining

Hoechst dyes bind noncovalently to DNA with a significant fluorescence enhancement. As a result, they are routinely used to stain the cell nucleus in diverse fluorescence imaging and flow cytometry applications. The short wavelengths necessary for their excitation, however, cause autofluorescence and photodamage. To overcome these limitations, we envisaged the possibility of integrating a borondipyrromethene (BODIPY) chromophore and a Hoechst ligand in the same molecular construct. Here, we report the synthesis of this BODIPY-Hoechst conjugate and demonstrate that the covalent connection of the two components has minimal influence on the photophysical properties of one and the binding ability of the other. Indeed, our compound binds to nuclear DNA, enabling cell imaging under excitation with green light from the BODIPY chromophore and the detection of its intense fluorescence.