A Competitive Pull-down Assay Using G-quadruplex DNA Linked Magnetic Nanoparticles to Determine Specificity of G-quadruplex Ligands.

Herein, we develop a competitive screening method in which G-quadruplex DNA linked magnetic nanoparticles pull down selective ligands for a particular quadruplex topology from a series of small molecules. The screening strategy is first optimized with known G-quadruplex ligands and then used with a new series of G-quadruplex interactive bis-triazolyl ligands that are synthesized by Cu(I)-catalyzed azide alkyne cycloaddition. The assay enables the identification of c-MYC and BCL2 G-quadruplex selective bis-triazole ligands that specifically target promoter G-quadruplexes in cancer cells.