An exonuclease-assisted amplification electrochemical aptasensor for Hg2+ detection based on hybridization chain reaction

作者：Bao Ting; Wen Wei; Zhang Xiuhua; Xia Qinghua; Wang Shengfu^*

来源：Biosensors and Bioelectronics, 2015, 70: 318-323.

DOI：10.1016/j.bios.2015.03.065

• Electrochemical aptasensor
• Hg2+
• Exonuclease III
• Target recycling
• Hybridization chain reaction

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.

• 出版日期2015-8-15
• 单位湖北大学