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Anal Chem. 2011 Dec 1;83(23):8871-6. doi: 10.1021/ac2006763. Epub 2011 Nov 3.

Bifunctional colorimetric oligonucleotide probe based on a G-quadruplex DNAzyme molecular beacon.

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State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, P. R. China.


A label-free bifunctional colorimetric oligonucleotide probe for DNA and protein detection has been developed on the basis of a novel catalytic molecular beacon consisting of two hairpin structures and a split G-quadruplex DNAzyme in the middle. The two loops of this molecular beacon consist of thrombin aptamer sequence and the complementary sequence of target DNA, which are utilized to sense single-stranded DNA and thrombin. The G-quadruplex DNAzyme can effectively catalyze the H(2)O(2)-mediated oxidation of 3,3',5,5'-tetramethylbenzidine sulfate to generate colorimetric signal. Upon addition of the target, the DNA or protein combines with one loop of the hairpin structures, and meanwhile drives the middle G-quadruplex DNAzyme to dissociate. This results in a decrease of catalytic activity, enabling the separate analysis of DNA and thrombin.

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