Figure 12.

Aptamer-based assay for HIV biomarker IFN-γ using a luminescent Ir(III) detection probe. (A) The assay utilized two aptamers, the first being an IFN-γ-specific aptamer (green) that was prehybridized to a G-quadruplex aptamer (blue). Addition of a sample resulted in the capture of IFN-γ by the first aptamer and liberation of the G-quadruplex aptamer, which underwent a structural switch to form guanine tetrads upon introduction of K⁺ ions. The G-quadruplexes were specific for a cyclometalated Ir(III) complex that produced phosphorescent signal that was correlated with IFN-γ concentration. (B) Structure of the cyclometalated Ir(III) complex. Adapted with permission from ref (139). Copyright 2015 Royal Society of Chemistry.