Tunable G-Quadruplex Ligands: Azobenzene Derivatives for Light-Controlled DNA Modulation.

During transcription, replication, and DNA repair, DNA unwinds to reveal guanine-rich sequences that form stable G-quadruplexes. In cancer cells, increased transcription and replication promote G4 formation, making them attractive therapeutic targets. G4s block DNA and RNA polymerases, inducing replication stress and causing toxic single- and double-strand breaks.