Quantitative Detection of G‐Quadruplex DNA in Live Cells Based on Photon Counts and Complex Structure Discrimination

Abstract

G‐quadruplex DNA undergoes structural polymorphism, leading challenging around using selectively recognizing probe to accurately detect G‐quadruplexes in vivo . Herein, we developed a selectively responsive probe, a tripodal cationic fluorescent probe, NBTE , which showed distinguishable fluorescence lifetime response between all kinds of G‐quadruplexes and other DNA topologies, and fluorescence quantum yield enhancing upon G‐quadruplexes binding. We determined two NBTE– G‐quadruplex complex structures with high fluorescence quantum yield by NMR method. The structures indicated NBTE interacted with G‐quadruplexes using three arms through π‐π stacking, differing from that with duplex DNA using two arms, which rationalized higher fluorescence quantum yield and lifetime response of NBTE upon G‐quadruplexes binding. Based on photon counts of FLIM, we detected the percentage of G‐quadruplex DNA in live cells with NBTE , and found G‐quadruplex DNA content in cancer cells is ~4 times that in normal cells, suggesting the potential applications of this probe in cancer cells detection.