期刊
BIOSENSORS & BIOELECTRONICS
卷 27, 期 1, 页码 148-152出版社
ELSEVIER ADVANCED TECHNOLOGY
DOI: 10.1016/j.bios.2011.06.032
关键词
DNAzyme; G-quadruplex; Hg2+; Cysteine; Structural switch
类别
资金
- National Natural Science Foundation of China [20975055]
- National Basic Research Program of China [2011CB707700]
- National Natural Science Foundation of Tianjin [08JCZDJC21200]
A simple and sensitive colorimetric Hg2+ detection method is reported, based on the Hg2+-mediated structural switch of an unlabeled oligonucleotide strand. In the absence of Hg2+, the oligonucleotide strand forms a stem-loop. A G-rich sequence in the strand is partially caged in the stem-loop structure and cannot fold into a G-quadruplex. In the presence of Hg2+,T-Hg2+-T coordination chemistry leads to the formation of another stem-loop structure and the release of the G-rich sequence. The released sequence folds into a G-quadruplex, which binds hemin to form catalytically active G-quadruplex DNAzymes. This is detected as an absorbance increase in a H2O2-2,2'-azinobis(3-ethylbenzothiozoline)-6-sulfonic acid (ABTS) reaction system using UV-vis absorption spectroscopy. This simple calorimetric sensor can detect aqueous Hg2+ at concentrations as low as 9.2 nM with high selectivity. Based on the strong binding interaction between Hg2+ and the sulfur-containing amino acid cysteine (Cys), and the competition between Cys and a oligonucleotide for Hg2+, the proposed Hg2+-sensing system can be further exploited as a Cys-sensing method. The method has a detection limit for Cys of 19 nM. (C) 2011 Elsevier B.V. All rights reserved.
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