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G-Quadruplex DNAzyme Molecular Beacon for Amplified Colorimetric Biosensing of Pseudostellaria heterophylla
Institute of Drug Research, Fujian Academy of Chinese Medicine, Fuzhou 350003, China
The College of Pharmacy, Fujian University of Traditional Chinese Medicine, Fuzhou 350122, China
The Second People's Hospital of Fujian Province, Fuzhou 350003, China
* Author to whom correspondence should be addressed.
Received: 12 December 2012; in revised form: 4 January 2013 / Accepted: 9 January 2013 / Published: 16 January 2013
Abstract: 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 × 10−10 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
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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.
Zheng Z, Han J, Pang W, Hu J. G-Quadruplex DNAzyme Molecular Beacon for Amplified Colorimetric Biosensing of Pseudostellaria heterophylla. Sensors. 2013; 13(1):1064-1075.
Zheng, Zhenzhu; Han, Jing; Pang, Wensheng; Hu, Juan. 2013. "G-Quadruplex DNAzyme Molecular Beacon for Amplified Colorimetric Biosensing of Pseudostellaria heterophylla." Sensors 13, no. 1: 1064-1075.