Electrochemical amplification for Hg(II) quantification by anchoring an enzymatically extended aptamer

Abstract

A novel indirect electrochemical approach is reported to improve the sensitivity of Hg²⁺ quantification in environmental water samples. This strategy is based on the Hg²⁺ induced selective interaction of thymine mismatched pairs in a thymine-rich aptamer DNA to improve the specificity, while template-independent terminal deoxynucleotidyl transferase (TdT) extended the 3′-OH aptamer termini with repeated bases and increased the sensitivity. The introduction of the target Hg²⁺ blocked aptamer extension. Taking advantage of an electrochemical platform, this aptamer-TdT based amplification sensor enabled the specific quantification of Hg²⁺ ion over a wide linear range from 2 pM to 20 nM with a low limit of detection equal to 0.1 pM. The proposed strategy is promising for the detection of other metal ions.

Keywords:

• Electrochemical amplification
• Hg(II) quantification
• terminal deoxynucleotidyl transferase
• thymine–Hg²⁺–thymine complex

Disclosure statement

The authors declare no competing financial interests.

Additional information

Funding

This research was supported by the Foundation of Yunnan Province [2017ZE027, 2016CP021], the Basic Research Foundation of Yunnan Tobacco Industry [2018JC04], and the Foundation of Key Laboratory of Tobacco Chemistry of Yunnan Province [KCFZ-2017-1096].