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. 2022 May 30;7(23):19622-19630.
doi: 10.1021/acsomega.2c01335. eCollection 2022 Jun 14.

Au NP-Decorated g-C3N4-Based Photoelectochemical Biosensor for Sensitive Mercury Ions Analysis

Mengjie Li  1   2 , Ying Wu  1   2 , Siyu An  1   2 , Zhitao Yan  1   2
Affiliations

Au NP-Decorated g-C3N4-Based Photoelectochemical Biosensor for Sensitive Mercury Ions Analysis

Mengjie Li et al. ACS Omega. .

Abstract

Herein, an efficient and feasible photoelectrochemical (PEC) biosensor based on gold nanoparticle-decorated graphitic-like carbon nitride (Au NPs@g-C3N4) with excellent photoelectric performance was designed for the highly sensitive detection of mercury ions (Hg2+) . The proposed Au NPs@g-C3N4 was first modified on the surface of the electrode, which possessed a remarkable photocurrent conversion efficiency and could produce a strong initial photocurrent. Then, the thymine-rich DNA (S1) was immobilized on the surface of the modified electrode via Au-N bonds. Subsequently, 1-hexanethiol (HT) was added to the resultant electrode to block nonspecific binding sites. Finally, the target Hg2+ was incubated on the surface of the modified glassy carbon electrode (GCE). In the presence of target Hg2+, the thymine-Hg2+-thymine (T-Hg2+-T) structure formed due to the selective capture capability of thymine base pairs toward Hg2+, resulting in the significantly decrease of the photocurrent. Thereafter, the proposed PEC biosensor was successfully used for sensitive Hg2+ detection, as it possessed a wide linear range from 1 pM to 1000 nM with a low detection limit of 0.33 pM. Importantly, this study demonstrates a new method of detecting Hg2+ and provides a promising platform for the detection of other heavy metal ions of interest.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Scheme 1
Scheme 1. Schematic Representation of the PEC Biosensor for Hg2+ Detection
Figure 1
Figure 1
SEM images of (A) g-C3N4 and (B) Au NPs@g-C3N4. (C) TEM image of Au NPs@g-C3N4.
Figure 2
Figure 2
XPS analysis of (a) the full region of Au NPs@g-C3N4, (b) the N 1s region, (c) the C 1s region, and (d) the Au 4f region.
Figure 3
Figure 3
Effect of (A) the H2O2 concentration in the detection solution and (B) the irradiation wavelength on the photocurrent.
Figure 4
Figure 4
PEC signals of g-C3N4 and Au NPs@g-C3N4.
Figure 5
Figure 5
Mechanisms for (A) photocurrent generation and (B) photocurrent quenching.
Figure 6
Figure 6
Photocurrent of (a) bare GCE, (b) Au NPs@g-C3N4/GCE, (c) S1/Au NPs@g-C3N4/GCE, (d) HT/S1/Au NPs@g-C3N4/GCE, and (e) Hg2+/HT/S1/Au NPs@g-C3N4/GCE.
Figure 7
Figure 7
(A) CV and (B) EIS responses of (a) bare GCE, (b) Au NPs@g-C3N4/GCE, (c) S1/Au NPs@g-C3N4/GCE, (d) HT/S1/Au NPs@g-C3N4/GCE, and (e) Hg2+/HT/S1/Au NPs@g-C3N4/GCE.
Figure 8
Figure 8
(A) Photocurrent with various Hg2+ concentrations. (B) Linear relationship between the photocurrent and the logarithm of the Hg2+ concentration. The insert in panel B presents the calibration curve of the photocurrent value vs the concentration of Hg2+ at a low concentration range.
Figure 9
Figure 9
(A) Exploration of the selectivity of the PEC biosensor. (B) Stability test of the biosensor at 1 nM Hg2+.
See this image and copyright information in PMC

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