Optical aptasensing of mercury(II) by using salt-induced and exonuclease I-induced gold nanoparticle aggregation under d
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ORIGINAL PAPER
Optical aptasensing of mercury(II) by using salt-induced and exonuclease I-induced gold nanoparticle aggregation under dark-field microscope observation Yanan Li 1 & Qingyun Liu 2 & Zhengbo Chen 1 Received: 26 June 2019 / Accepted: 26 September 2019 # Springer-Verlag GmbH Austria, part of Springer Nature 2019
Abstract An optical method for determination of Hg(II) is described that exploits the aggregation of gold nanoparticles (AuNPs) under dark-field microscope (DFM) observation. This assay is based on the use of a Hg(II)-specific aptamer, AuNPs modified with complementary DNA strands, and exonuclease I (Exo I). In the absence of Hg(II), the added dsDNA prevents salt-induced aggregation of the green-colored AuNPs. If Hg(II) is added, the aptamer will capture it to form T-Hg(II)-T pairs, and the complementary strand is digested by Exo I. On addition of a solution of NaCl, the AuNPs will aggregate. This is accompanied by a color change from green to orange/red) in the dark-field image. By calculating the intensity of the orange/red dots in the dark-field image, concentration of Hg(II) can be accurately determined. The limit of detection is as low as 36 fM, and response is a linear in the 83 fM to 8.3 μM Hg(II) concentration range. Keywords Mercury assay . Gold nanoparticle aggregation . Dark-field microscope . Exonuclease I . Red nanodots . Green nanodots . Aptamer . High sensitivity
Introduction It is regarded that Hg2+ ions are one of the most dangerous metal ions in comparasion with other toxic metal ions because it’s poisonous and harmful to human health [1, 2]. The United States Environmental Protection Agency (EPA) has specified 10 nM to be the maximum permissible level for Hg2+ in drinking water [3]. Therefore, the determination of trace levels of Hg2+ is vital for water quality control, public health, and environmental monitoring.
A method based on intensity of AuNPs for highly sensitive and selective Hg2+ sensing using dark-field microscope Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00604-019-3876-9) contains supplementary material, which is available to authorized users. * Zhengbo Chen [email protected] 1
Department of Chemistry, Capital Normal University, Beijing 100048, China
2
College of Chemical and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590, China
To achieve this aim, numerous of implemental detection approaches, including inductively coupled plasma atomic emission spectrometry [4], cold vapor technique with atomic absorption spectrometry [5], circular dichroism [6], inductively coupled plasma mass spectrometry [7], impedance spectrometry [8], and surface-enhanced raman scaterring [9], etc., have been constructed. These methods possess excellent sensitivity, however, they usually have the shortcomings of being time-consuming and labor-intensive, and the apparatus requirements are complex. In this context, dark-field microscope (DFM) emerges as a great alternative, as it is simple,
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