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Electrochemiluminescence Immunosensor Based on Au Nanocluster and Hybridization Chain Reaction Signal Amplification for Ultrasensitive Detection of Cardiac Troponin I
journal contribution
posted on 2019-10-15, 12:05 authored by Liping Zhu, Jing Ye, Mengxia Yan, Qiuju Zhu, Shuang Wang, Jianshe Huang, Xiurong YangMeasurement of cardiac
troponin I in the blood is crucial for the
early diagnosis of acute myocardial infarction. Herein, a novel and
ultrasensitive electrochemiluminescence (ECL) immunosensor has been
developed for determination of cardiac troponin I (cTnI) by using
Au nanoclusters and hybridization chain reaction (HCR) signal amplification.
In this ECL immunosensor, Au nanoclusters were dual-labeled at each
end of hairpin DNA (H1 and H2) and acted as
the luminophore. DNA initiator strands (T1) and secondary
antibody (Ab2) were conjugated on Au nanoparticles (AuNPs)
to obtain a smart probe (Ab2-AuNP-T1). In the
presence of target cTnI, the sandwiched immunocomplex composed of
cTnI, Ab1, and Ab2-AuNP-T1 was formed.
Then the initiator strands T1 of Ab2-AuNP-T1 opened the hairpin DNA structures and triggered a cascade
of hybridization events. Consequently, a large number of Au NCs were
indirectly modified on the surface of the electrode, which could react
with the coreactant (K2S2O8) and
emit a strong ECL signal. Under the optimal conditions, the immunosensor
exhibited a wide detection range for cTnI from 5 fg/mL to 50 ng/mL
and a low detection limit of 1.01 fg/mL (S/N = 3). Because of the
excellent specificity, stability, and reproducibility of the proposed
ECL-HCR sensor, it has a great application prospect for cTnI detection
in clinical diagnosis.