4.7 Article

Catalytic hairpin assembly assisted target-dependent DNAzyme nanosystem coupled with AgPt@Thi for the detection of lead ion

Journal

ANALYTICA CHIMICA ACTA
Volume 1205, Issue -, Pages -

Publisher

ELSEVIER
DOI: 10.1016/j.aca.2022.339735

Keywords

Pb2+; Catalytic hairpin assembly; Pb2+-dependent DNAzyme; Electrochemical biosensor

Funding

  1. National Natural Science Foundation of China [21106073]
  2. Major Science and Technology Innovation Projects in Shandong Province [2018CXGC1102]

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An ultrasensitive electrochemical biosensor based on catalytic hairpin assembly and DNAzyme signal amplification strategy is proposed for the detection of lead ions. The biosensor utilizes polyethyleneimine-reduced graphene oxide combined with gold@silver nanosheets as electrode substrate modification materials. The biosensor demonstrates a good linear relationship and low detection limit, enabling trace detection of lead ions in tap water samples and providing a platform for the detection of other targets.
An ultrasensitive electrochemical biosensor for detection of lead ions (Pb2+) is proposed based on catalytic hairpin assembly and target-induced DNAzyme signal amplification strategy. Polyethyleneimine-reduced graphene oxide (PEI-rGO) combined with gold@silver nanosheets (Au@Ag NSs) are used as electrode substrate modification materials, which not only increase the specific surface area but also exhibit stronger conductivity than pure PEI-rGO or Au@Ag NSs. Hairpin chain 1 (HP1) is immobilized on the surface of modified electrode by Au-S. Then trigger (Tr) DNA can induce the opening of the HP1 hairpin, thus exposing the binding sequence to hybridize with Hairpin chain 2 (HP2) and catalyzing the opening and binding of the hairpin HP2. The process is cyclic and will produce abundant HP1-HP2 duplex strands. When Pb2+ is present, it can catalyze DNAzyme (Pb2+-HP2) to specifically cut the substrate chain HP1, and only a partial sequence of HP1 remains on the surface of the electrode. Finally, the signal probe (AgPt@Thi-CP) can be hybridized with the part of the HP1 sequence after being cut to generate a significant electrical signal. Under optimal conditions, the Pb2+ concentration measured by prepared electrochemical biosensor has a good linear relationship in the range of 0.05 pM-5 nM, and the detection limit is 0.028 pM. This method can be used for the trace detection of Pb2+ in tap water samples, and it also provides a platform for the detection of other targets. (C) 2022 Elsevier B.V. All rights reserved.

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