Visualization of G-quadruplexes in gel and in live cells by a near-infrared fluorescent probe

G-quadruplexes, one of the most significant secondary structure of nucleic acid, are formed by stacking G quartets, which received broad interests due to their involvement in telomere function, gene transcription and recombination. As for ligand, better selectivity for G-quadruplex against other DNA or RNA structures and higher ability to stabilize G-quadruplex are necessary. In addition, developing a new probe to recognize G-quadruplex is desired for utilizing G-quadruplex structure to relevant biological processes. In this study, we report a Cy5 labelled ligand (named PDP-Cy5) developed as a near-infrared fluorescent ligand for G-quadruplexes both in DNA and RNA. The results indicated that PDP-Cy5 selectively induced the formation of intramolecular G-quadruplexes with strong binding affinity. Furthermore, this Cy5 labelled ligand can effectively stabilize G-quadruplexes. Moreover, the direct visualization of G-quadruplexes in gel, even on cell level is realized by using PDP-Cy5.