Journal
BIOSENSORS & BIOELECTRONICS
Volume 70, Issue -, Pages 318-323Publisher
ELSEVIER ADVANCED TECHNOLOGY
DOI: 10.1016/j.bios.2015.03.065
Keywords
Electrochemical aptasensor; Hg2+; Exonuclease III; Target recycling; Hybridization chain reaction
Categories
Funding
- National Natural Science Foundation of China [21175032, 21475032]
- Natural Science Fund for Creative Research Groups of Hubei Province of China [2014CFA015]
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In this work, a novel electrochemical aptasensor was developed for Hg2+ detection based on exonuclease-assisted target recycling and hybridization chain reaction (HCR) dual signal amplification strategy. The presence of Hg2+ induced the T-rich DNA partly folded into duplex-like structure via the Hg2+ mediated T-Hg2+-T base pairs, which triggered the activity of exonuclease Ill (Exo III). Exo III selectively digested the double-strand DNA containing multiple T-Hg2+-T base pairs from its 3'-end, the released Hg2+ participated analyte recycle. With each digestion cycle, a digestion product named as help DNA was obtained, which acted as a linkage between the capture DNA and auxiliary DNA. The presence of help DNA and two auxiliary DNA collectively facilitated successful HCR process and formed long double-stranded DNA. [Ru(NH3)(6)](3+) was used as redox indicator, which electrostatically bound to the double strands and produced an electrochemical signal. Exo III-assisted target recycling and HCR dual amplification significantly improved the sensitivity for Hg2+ with a detection limit of 0.12 pM (S/N=3). Furthermore, the proposed aptasensor had a promising potential for the application of Hg2+ detection in real aquatic sample analysis. (C) 2015 Elsevier B.V. All rights reserved.
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