Fluorescence turn-on probes for intracellular RNA distribution and their imaging in confocal and two-photon fluorescence microscopy

We have synthesized four indole derivatives (INS1, IND1, INS2 and IND2) successfully, and experimental results of biochemical RNA fluorescence assays and direct intracellular imaging demonstrated that they are potential highly RNA-selective fluorescent turn-on probes possessing good counterstain compatibility with the classic DNA-staining dye DAPI. Moreover, these sensors exhibit large two-photon excited fluorescence action absorption cross-section in the presence of RNA and are also capable of imaging intracellular RNA in two-photon fluorescence microscopy.