Deep-red light-up signaling of benzo[c,d]indole-quinoline monomethine cyanine for imaging of nucleolar RNA in living cells and for sequence-selective RNA analysis
Analytical chemistry | 10 Oct 2019
Y Yoshino, Y Sato and S Nishizawa
RNA-binding small probes with deep-red emission are promising for RNA analysis in the biological media without suffering from the background fluorescence. Here, benzo[c,d]indole-quinoline (BIQ), an asymmetric monomethine cyanine analogue, was newly developed as a novel RNA-selective probe with light-up signaling ability in the deep-red spectral range. BIQ features the significant light-up response (105-fold) with the emission maximum at 657 nm as well as the improved photostability over the commercially available RNA-selective probe, SYTO RNA select. BIQ was successfully applied to the fluorescence imaging of nucleoli RNAs in the living cells with negligible cytotoxicity. Furthermore, we found the useful ability of BIQ as a base surrogate integrated in the peptide nucleic acid (PNA) oligonucleotides for RNA sequence analysis. BIQ base surrogate functioned as the deep-red light-up base surrogate in forced intercalation (FIT) and triplex-forming FIT (tFIT) systems for the sequence-selective detection of single-stranded and double-stranded RNAs, respectively.
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