Single-Molecule MicroRNA Electrochemiluminescence Detection Using Cyclometalated Dinuclear Ir(III) Complex with Synergistic Effect

作者：Tai-Bao Gao, Jingjing Zhang, Jing Wen, Xue-Xiao Yang, Haibo Ma, Deng‐Ke Cao, Dechen Jiang · 发表于：Analytical Chemistry · 年份：2019 · DOI：10.1021/acs.analchem.9b04431 · 被引用次数：37 · 研究领域：Advanced biosensing and bioanalysis techniques、DNA and Nucleic Acid Chemistry、RNA and protein synthesis mechanisms

The realization of electrochemiluminescence (ECL) detection at the single-molecule level is a longstanding goal of ECL assay that requires a novel ECL probe with significantly enhanced luminescence. Here, the synergistic effect of electrochemiluminescence (ECL) is observed unprecedentedly in a new cyclometalated dinuclear Ir(III) complex [Ir 2 (dfppy) 4 (imiphenH)]PF 6 ( 1 ·PF 6, PF 6 – = hexafluorophosphate) in which two {Ir(dfppy) 2 } + units are bridged by an imiphenH – ligand. The ECL intensity from complex 1 ·PF 6 is 4.4 and 28.7 times as high as that of its reference mononuclear complexes 2 and 3 ·PF 6, respectively. Theoretical calculation reveals that the S 0 to S 1 excitation is a local excitation in 1 ·PF 6 with two electron-coupled Ir(III) centers, which contributes to the enhanced ECL. The synergistic effect of ECL in 1 ·PF 6 can be used to detect microRNA 21 at the single-molecule level (microRNA 21: UAGCUUAUCAGACUGAUGUUGA), with detectable ECL emission from this complex intercalated in DNA/microRNA 21 duplex as low as 90 helix molecules. The finding of the synergistic effect of ECL will not only provide a novel strategy for the modulation of ECL intensity but also enable the detection of microRNA at the single-molecule level.