A voltammetric biosensor for mercury(II) using reduced graphene oxide@gold nanorods and thymine-Hg(II)-thymine interaction
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The presented voltammetric mercury(II) sensor is based on the specific interaction between Hg(II) ion and thymine-thymine base pairs. Reduced graphene oxide is functionalized with gold nanorods and then loaded with thionine and streptavidin (RGO@AuNR-TH-SA). A T-rich thiolated DNA (S1) is firstly immobilized on a gold electrode. In the presence of Hg (II), the T-rich biotin-DNA (biotin-S2) binds to S1 via T-Hg(II)-T interaction. Then, the RGO@AuNR-TH-SA is linked to the gold electrode by specific binding between SA and biotin-S2. This produces an electrochemical signal (at −0.208 V vs. Ag/AgCl) of TH that depends on the concentration of Hg (II). The peak current increases linearly in the 1 to 200 nM Hg (II) concentration range, and the detection limit is 0.24 nM. The sensor is highly selective for Hg (II) over other environmentally relevant metal ions, even at concentration ratios of >1000.
KeywordsThionine Streptavidin-biotin Differential pulse voltammetry Signal amplification
This study was funded by the Natural Science Foundation of Henan Province (182300410188), the Fundamental Research Funds for the Henan Provincial Colleges and Universities in Henan University of Technology (2016RCJH04), and Key Scientific and Technological Project of Henan Province (192102310255).
Compliance with ethical standards
The author(s) declare that they have no competing interests.
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