Real-time fluorescence detection of Hg2+ ions with high sensitivity by exponentially isothermal oligonucleotide amplification

Abstract

A new sensitive assay for Hg²⁺ ions has been demonstrated in this work based on isothermal exponential amplification reaction (EXPAR). In the presence of Hg²⁺ ions, a thymine (T)-rich oligonucleotide probe will firstly combine with a T-rich template through Hg²⁺-mediated T–Hg²⁺–T interaction and subsequently trigger the EXPAR reaction. EXPAR is a simple, fast and highly efficient amplification technique, which can provides 10⁶–10⁹ fold amplification under isothermal conditions within minutes. Therefore, with real-time fluorescent detection of EXPAR products triggered by Hg²⁺ ions, high sensitivity is achieved and as low as 100 pM Hg²⁺ ions can be accurately determined in a 10 μL reaction system. Furthermore, due to the specific binding between Hg²⁺ and thymine, even 10–100 fold excess of other metal ions do not interfere with the detection of Hg²⁺ ions, showing high specificity of this proposed assay.