Yong-Xi Z.,Xian University of Science and Technology |
Lin Q.,Xian University of Science and Technology |
Wei-Jun Y.,Shaanxi Branch of China National Tobacco Corporation |
Shuai W.,Shaanxi Branch of China National Tobacco Corporation |
Ya-Ling W.,Shaanxi Branch of China National Tobacco Corporation
Fenxi Huaxue/ Chinese Journal of Analytical Chemistry | Year: 2012
A fluorescence sensing system was developed for the detection of Pb2+ with excellent sensitivity and selectivity based on Pb2+-dependent DNAzyme (8-17E DNAzyme) with nicking enzyme (Nt.BbvCI)-assisted signal cascade amplification strategy. In the presence of Pb2+, the 8-17E DNAzyme can catalyze the cleavage of its substrate. And subsequently, the partial substrate strand dissociated from DNAzyme could hybridize with molecular beacon (MB), resulting in the restoration of fluorescence signal as well as the formation of the double-stranded recognition site for nicking endonuclease (Nt.BbvCI). After the Nt.BbvCI mediated the cleavage of MB, the released partial substrate strand could hybridize with another MB probe again and be re-used for the second cycle of cleavage. Eventually, each target-induced partial substrate strand can trigger many cycles of cleavage to achieve the amplified fluorescence detection of Pb2+. This new design avoids the modification on DNAzyme and substrate, and significantly improves the sensitivity with a detection limit down to 1.0 × 10-10 M. Moreover, it also exhibited satisfactory selectivity for Pb2+ detection, even in the presence of 2 times concentrations of Zn2+ and 5 times concentrations of each other interferential metal ions. Furthermore, this proposed method was successfully used for the determination of Pb2+ in river water samples with recoveries from 96.1% to 108%. Copyright © 2012, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences. Published by Elsevier Limited. All rights reserved.
Qi L.,Xian University of Science and Technology |
Zhao Y.,Xian University of Science and Technology |
Yuan H.,Shaanxi Branch of China National Tobacco Corporation |
Bai K.,Shaanxi Branch of China National Tobacco Corporation |
And 3 more authors.
Analyst | Year: 2012
In this work, a fluorescent sensing strategy was developed for the detection of mercury(ii) ions (Hg 2+) in aqueous solution with excellent sensitivity and selectivity using a target-induced DNAzyme cascade with catalytic and molecular beacons (CAMB). In order to construct the biosensor, a Mg 2+-dependent DNAzyme was elaborately designed and artificially split into two separate oligonucleotide fragments. In the presence of Hg 2+, the specific thymine-Hg 2+-thymine (T-Hg 2+-T) interaction induced the two fragments to produce the activated Mg 2+-dependent DNAzyme, which would hybridize with a hairpin-structured MB substrate to form the CAMB system. Eventually, each target-induced activated DNAzyme could catalyze the cleavage of many MB substrates through true enzymatic multiple turnovers. This would significantly enhance the sensitivity of the Hg 2+ sensing system and push the detection limit down to 0.2 nM within a 20 min assay time, much lower than those of most previously reported fluorescence assays. Owning to the strong coordination of Hg 2+ to the T-T mismatched pairs, this proposed sensing system exhibited excellent selectivity for Hg 2+ detection, even in the presence of 100 times of other interferential metal ions. Furthermore, the applicability of the biosensor for Hg 2+ detection in river water samples was demonstrated with satisfactory results. These advantages endow the sensing strategy with a great potential for the simple, rapid, sensitive, and specific detection of Hg 2+ from a wide range of real samples. © 2012 The Royal Society of Chemistry.