title: Identifying G-quadruplex-binding ligands using DNA-functionalized gold nanoparticles.
abstract: The G-rich overhang of human telomere tends to form a G-quadruplex structure, and G-quadruplex formation can effectively inhibit telomerase activity in most cancer cells. Therefore, it is important to identify the formation and properties of the G-quadruplex, with the particular aim of selecting G-quadruplex-binding ligands that could potentially lead to the development of anticancer therapeutic agents. With this goal in mind, we report a fluorescence resonance energy transfer (FRET) assay system for the identification of G-quadruplex ligands using DNA-functionalized gold nanoparticles (DNA-GNPs) as the fluorescence quencher and a carboxyfluorescein (FAM)-tagged human telomeric sequence (F-GDNA) as the recognition probe. A thiolated complementary strand of human telomeric DNA (cDNA), which first adheres to the surface of the GNPs and then hybridizes with F-GDNA, results in the fluorescence quenching of F-GDNA by the GNPs. However, fluorescence is restored when single-stranded F-GDNA folds into a G-quadruplex structure upon the binding of quadruplex ligands, leading to the release of F-GDNA from the surface of the GNPs. Combined data from fluorescence measurements and CD spectroscopy indicated that ligands selected by this FRET method could induce GDNA to form a G-quadruplex. Therefore, this FRET G-quadruplex assay is a simple and effective approach to identify quadruplex-binding ligands, and, as such, it promises to provide a solid foundation for the development of novel anticancer therapeutic agents.
authors.affiliation: Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemistry Engineering, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Qiao
authors.forename: Jing
authors.initials: J
authors.lastname: Deng
authors.forename: Yan
authors.initials: Y
authors.lastname: Jin
authors.forename: Guozhen
authors.initials: G
authors.lastname: Chen
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
mesh_terms: D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D054856:G-Quadruplexes; D006046:Gold / Q000737:chemistry*; D006801:Humans; D008024:Ligands; D053768:Metal Nanoparticles / Q000737:chemistry*; D008954:Models, Biological
chemical_list: D008024:Ligands; D006046:Gold; D004247:DNA