A 2,7-carbazole-based dicationic salt for fluorescence detection of nucleic acids and two-photon fluorescence imaging of RNA in nucleoli and cytoplasm

A new carbazole-derived dicationic compound, namely 2,7-bis(1-hydroxyethyl-4-vinylpyridinium iodine)-N-ethyl-carbazole (2,7-9E-BHVC), with a large two-photon action absorption cross section in nucleic acids has been obtained. Moreover, it possesses the potential of imaging RNA in nucleoli and cytoplasm in two-photon fluorescence microscopy and exhibits good counterstain compatibility with the commercial fluorescent nucleic dye DAPI.