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Sensors 2013, 13(1), 1064-1075; doi:10.3390/s130101064

G-Quadruplex DNAzyme Molecular Beacon for Amplified Colorimetric Biosensing of Pseudostellaria heterophylla

1 Institute of Drug Research, Fujian Academy of Chinese Medicine, Fuzhou 350003, China 2 The College of Pharmacy, Fujian University of Traditional Chinese Medicine, Fuzhou 350122, China 3 The Second People's Hospital of Fujian Province, Fuzhou 350003, China
* Author to whom correspondence should be addressed.
Received: 12 December 2012 / Revised: 4 January 2013 / Accepted: 9 January 2013 / Published: 16 January 2013
(This article belongs to the Section Biosensors)
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With an internal transcribed spacer of 18 S, 5.8 S and 26 S nuclear ribosomal DNA (nrDNA ITS) as DNA marker, we report a colorimetric approach for authentication of Pseudostellaria heterophylla (PH) and its counterfeit species based on the differentiation of the nrDNA ITS sequence. The assay possesses an unlabelled G-quadruplex DNAzyme molecular beacon (MB) probe, employing complementary sequence as biorecognition element and 1:1:1:1 split G-quadruplex halves as reporter. In the absence of target DNA (T-DNA), the probe can shape intermolecular G-quadruplex structures capable of binding hemin to form G-quadruplex-hemin DNAzyme and catalyze the oxidation of ABTS2− to blue-green ABTS•− by H2O2. In the presence of T-DNA, T-DNA can hybridize with the complementary sequence to form a duplex structure, hindering the formation of the G-quadruplex structure and resulting in the loss of the catalytic activity. Consequently, a UV-Vis absorption signal decrease is observed in the ABTS2−-H2O2 system. The “turn-off” assay allows the detection of T-DNA from 1.0 × 10−9 to 3.0 × 10−7 mol·L−1 (R2 = 0.9906), with a low detection limit of 3.1 × 1010 mol·L−1. The present study provides a sensitive and selective method and may serve as a foundation of utilizing the DNAzyme MB sensor for identifying traditional Chinese medicines.
Keywords: G-quadruplex DNAzyme; molecular beacon; colorimetric; Pseudostellaria heterophylla G-quadruplex DNAzyme; molecular beacon; colorimetric; Pseudostellaria heterophylla
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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Zheng, Z.; Han, J.; Pang, W.; Hu, J. G-Quadruplex DNAzyme Molecular Beacon for Amplified Colorimetric Biosensing of Pseudostellaria heterophylla. Sensors 2013, 13, 1064-1075.

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