Here, we have successfully developed benzo[c,d]indole-quinoline monomethine cyanine (BIQ) (Fig.1A) as a novel RNA-selective fluorescent probe . BIQ features the remarkable light-up response (105-fold) with RNA selectivity in the deep-red spectral region (λem = 657 nm) as well as the improved photostability over the commercially available RNA-selective probe. Significantly, BIQ was applicable to the fluorescence imaging of nucleolar RNAs in the living cells (Fig.1B). We have also developed BIQ derivative as the brightest fluorescent probe for the imaging of nucleoli RNAs in the living cells . By using these promising probes, we are now undertaking further studies on various kinds of bio-analytical applications including drug screening and virus RNA detection.
Figure 1. (A) Chemical structure of BIQ and (B) fluorescence image of living MCF7 cells stained by BIQ with nuclear counterstaining with Hoechst 33342.