A parallel G-quadruplex-selective iridium(III) complex has been synthesized and employed as a luminescent probe in a label-free G-quadruplex-based detection assay for Ca2+ ions in aqueous solution. In this assay, a guanine-rich oligonucleotide (G4, 5'-G4T4G4-3') initially exists in an antiparallel G-quadruplex conformation, resulting in a low luminescence signal. Upon incubation with Ca2+ ions, the antiparallel G-quadruplex is induced into a parallel G-quadruplex conformation, which greatly enhances the luminescence emission of the iridium(III) probe. This method was highly sensitive for Ca2+ ions with a limit of detection in the nanomolar range, and was selective for Ca2+ over other metal ions.
Scopus Subject Areas
- Molecular Biology
- Biochemistry, Genetics and Molecular Biology(all)
- Metal complex