Label-free luminescent detection of LMP1 gene deletion using an intermolecular G-quadruplex-based switch-on probe

We have synthesized a series of luminescent iridium(III) complexes and investigated their ability to act as luminescent split G-quadruplex probes. After screening, the iridium(III) complex 1 [Ir(2-phenylquinoline)2(3,4,7,8-tetramethyl-1,10-phenanthroline)]PF6 was validated as a highly-selective G-quadruplex probe and was utilized to construct a label-free intermolecular G-quadruplex-based assay for the selective and sensitive detection of LMP1 gene deletion. This "mix-and-detect" assay is simple and selective, and could detect down to 10 nM of the target gene in aqueous solution with a linear range from 10 to 500 nM. We also investigated the performance of our split G-quadruplex-based sensing platform for LMP1 gene deletion in the presence of cellular debris, demonstrating the robustness of this sensing system in biological samples. Comparative assays were also performed using either organic dyes or labeled oligonucleotides as signal-transducing agents.