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Issue 6, 2019
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Silver-ion-mediated Mg2+-dependent DNAzyme activity for amplified fluorescence detection of cysteine

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Abstract

In this paper, by taking advantage of the fact that silver ions could mediate the Mg2+-dependent DNAzyme (Mgzyme) activity, we for the first time developed a turn-on fluorescent biosensor for amplified cysteine (Cys) detection. Because Mgzyme can interact with the silver ion and form cytosine–Ag+–cytosine (C–Ag+–C) base pairs, the conformation of its catalytic core was changed. As a result, the catalytic activity of Mgzyme was suppressed and the Mgzyme–Ag+ complex could not initiate the cleavage reaction. Therefore, the background fluorescence of the biosensor was very low. In the presence of Cys, Cys can bind tightly to the silver ion and disrupt the C–Ag+–C base pairs in the Mgzyme–Ag+ complex, leading to the restoration of Mgzyme activity. The activated Mgzyme could hybridize with the MB substrate and undergo many cleavage cycles, resulting in a significant increase of fluorescence intensity. This designed strategy provided amplified fluorescence detection of cysteine, with a detection limit of 2 nM. Moreover, the strong binding between Cys and Ag+ ensured that the biosensor had a desirable selectivity for Cys. This sensing system was also used to detect Cys in human urine samples and displayed satisfying results.

Graphical abstract: Silver-ion-mediated Mg2+-dependent DNAzyme activity for amplified fluorescence detection of cysteine

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Publication details

The article was received on 27 Nov 2018, accepted on 12 Jan 2019 and first published on 16 Jan 2019


Article type: Paper
DOI: 10.1039/C8AN02308E
Citation: Analyst, 2019,144, 1982-1987

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    Silver-ion-mediated Mg2+-dependent DNAzyme activity for amplified fluorescence detection of cysteine

    X. Zhao, L. Zhang, S. Zhao, X. Cui, L. Gong, R. Zhao, B. Yu and J. Xie, Analyst, 2019, 144, 1982
    DOI: 10.1039/C8AN02308E

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