An electrochemiluminescent assay for high sensitive detection of mercury (II) based on isothermal rolling circular amplification

In this study, we firstly demonstrated that Bst DNA polymerase shows specific recognition and function on the T–Hg2+–T biomimetic structure. Based on this, a novel available electrochemiluminescence (ECL) sensor for Hg2+ has been developed. In this strategy, magnet beads tagged primer was designed to complementary to the region of the circular padlock probe but with two T–T mismatches at the 3′ end. The mismatched primers cannot be extended by Bst DNA polymerase in the absence of Hg2+. Stable T–Hg2+–T can be formed in the presence of Hg2+, thus induces the elongation and amplification reaction by DNA polymerase with a rolling circular amplification (RCA) mechanism. Subsequently, the resulted RCA products are hybridized with the tris (bipyridine) ruthenium (TBR)-tagged probes and detected by ECL platform. Current method shows a sub-nanomolar sensitivity and excellent selectivity over a spectrum of interference metal ions.

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► Bst DNA polymerase shows specific function on the T–Hg2+–T biomimetic structure.
► T–Hg2+–T can be formed in the presence of Hg2+, thus induces the RCA reaction.
► Sub-nanomolar sensitivity and excellent selectivity were achieved for Hg2+ detection.