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Cyclometalated Iridium‐Complex‐Based Label‐Free Supersandwich Electrogenerated Chemiluminescence Biosensor for the Detection of Micro‐RNA
Author(s) -
Zhao Ying,
Yang Xiaolin,
Han Danjuan,
Qi Honglan,
Gao Qiang,
Zhang Chengxiao
Publication year - 2017
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201600881
Subject(s) - chemiluminescence , chemistry , biosensor , detection limit , ligand (biochemistry) , electrochemiluminescence , acetonitrile , iridium , photochemistry , electrochemistry , aqueous solution , phosphorescence , analytical chemistry (journal) , electrode , fluorescence , chromatography , catalysis , organic chemistry , biochemistry , receptor , physics , quantum mechanics
The synthesis and characterization of compounds as electrogenerated chemiluminescence (ECL) reagents are crucial in fundamental research for ECL biosensors. In this work, a new cyclometalated iridium(III) complex, [(bt) 2 Ir(dmphen)](PF 6 ), was synthesized by using 2‐phenylbenzothiazole (bt) as theC ∧ N main ligand and 5,6‐dimethyl‐1,10‐phenanthroline (dmphen) as theN ∧ N ancillary ligand. The photophysical, electrochemical, and ECL properties of this complex were extensively studied in acetonitrile solvent and aqueous solution. This complex displayed yellow‐green photoluminescence with a maximum wavelength at 522 nm, a reversible one‐electron oxidation wave at E 1/2 =+1.51 V (vs. SCE), and a reversible one‐electron reduction wave at −1.29 V (vs. SCE). Typically, in the annihilation process, the ECL efficiency of this complex was 12 times higher than that of Ru(bpy) 3 2+ . More importantly, a highly sensitive ECL method for the determination of micro‐RNA at the sub‐picomolar level was developed on basis of employing this complex as an ECL intercalator and signal amplification by using the supersandwich model. Compared with Ru(phen) 3 Cl 2 and [(bt) 2 Ir(dcbpy)](PF 6 ), this complex showed a relatively low background and the highest increased ratio as an ECL intercalator in the developed system. The increased ECL intensity was directly proportional to the concentration of the micro‐RNA in the range of 0.1 to 10 pM, with a detection limit of 13 fM. The developed method can effectively discriminate target micro‐RNA122 from two‐base mismatched micro‐RNA122. This work demonstrates that this cyclometalated iridium(III) complex is an effective alternative intercalator for ECL determination of the micro‐RNA. It is expected that this complex will be extended to design various analytical platforms for the detection of diverse analytes such as DNA/RNA, DNAzyme/target, and aptamer/targets.