Dual triggers induced disassembly of DNA polymer decorated silver nanoparticle for ultrasensitive electrochemical Pb

In this work, a new label-free biosensor based on highly effective decomposition of a branched DNA polymer and target-transition recycling amplification was designed for ultrasensitive electrochemical determination of lead ion (Pb2+). The branched DNA polymer formed by hybridization chain reaction (HCR) was first immobilized on electrode and served as the carrier for loading abundant silver nanoparticle (AgNPs) to generate an extremely high initial current signal output. Then, the molecular triggers T1 and T2, which were produced through a target-transition recycling amplification, could respectively disassemble the backbone and side chain of the branched DNA polymer with remarkably decreased current for sensitive detection of Pb2+. Compared with traditional one-trigger induced disassembly strategy, the proposed approach exhibited higher decomposition efficiency. The experimental data showed that this developed biosensor had a superior performance for Pb2+ detection with a low detection limit down to 0.24 pM. Furthermore, the established strategy set up a new way to achieve the ultrasensitive detection of other metal ions.