期刊
MICROCHIMICA ACTA
卷 185, 期 12, 页码 -出版社
SPRINGER WIEN
DOI: 10.1007/s00604-018-3097-7
关键词
Mercury specific oligonucleotide; Bridging strand; Signal amplification; Layer-by-layer hybridization; Hexacyanoferrate; Electrochemical impedance spectroscopy; Atomic force microscopy; Water sample
资金
- National Natural Science Foundation of China [21802064, 21575027]
- Natural Science Foundation of Fujian Province [2018J01435, 2017J01419]
- Foundation of Key Laboratory of Sensor Analysis of Tumor Marker from Ministry of Education, Qingdao University of Science and Technology
An impedimetric method is described for ultrasensitive analysis of mercury(II). It is based on thymine-Hg(II)-thymine interaction which causes the disintegration of multiple-sandwich structured DNA chains. DNA strands were selected that are partially complementary to the T-rich Hg(II)-specific oligonucleotides (MSO). They were immobilized on a gold electrode via Au-S interaction. Next, the MSO and the bridging strands (BS) that can connect adjacent MSOs were alternately attached through layer-by-layer hybridization. Thus, a multiple-sandwich structured interface in created that carries numerous MSOs. This leads to a change-transfer resistance (R-ct) values of the electrode-electrolyte interface at faradic electrochemical impedance spectroscopy measurements in the presence of the hexacyanoferrate(II)/(III) redox probe at 0.2 V (vs. Ag/AgCl). If Hg(II) is added to the solution, the MSOs selectively interact with Hg(II) to produce T-Hg(II)-T structures. Hence, the multiple-sandwich hybridization chains become disintegrated, and this causes a decrease in resistivity. The effect can be used to quantify Hg(II) over an analytical range that extends over four orders of magnitude (1 fM to 10 pM), and it has a 0.16 fM limit of detection under optimal conditions.
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