Journal
MICROCHIMICA ACTA
Volume 185, Issue 12, Pages -Publisher
SPRINGER WIEN
DOI: 10.1007/s00604-018-3097-7
Keywords
Mercury specific oligonucleotide; Bridging strand; Signal amplification; Layer-by-layer hybridization; Hexacyanoferrate; Electrochemical impedance spectroscopy; Atomic force microscopy; Water sample
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Funding
- 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
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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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