A pyrene-based two-photon excitable fluorescent probe to visualize nuclei in live cells

The two-photon absorption properties of a pyrene-pyridinium dye (1) were studied for potential application in two-photon spectroscopy. When probe1was used in cellular two-photon fluorescence microscopy imaging, it allowed the visualization of nuclei in live cells with a relatively low probe concentration (such as 1 mu M). Spectroscopic evidence further revealed that probe1interacted with DNA as an intercalator. The proposed DNA intercalation properties of probe1were consistent with the experimental findings that suggested that the observed nucleus staining ability is dependent on the substituents on the pyridinium fragment of the probe.