Issue 16, 2021

Antibody-powered DNA switches to initiate the hybridization chain reaction for the amplified fluorescence immunoassay

Abstract

Designing antibody-powered DNA nanodevice switches is crucial and fascinating to perform a variety of functions in response to specific antibodies as regulatory inputs, achieving highly sensitive detection by integration with simple amplified methods. In this work, we report a unique DNA-based conformational switch, powered by a targeted anti-digoxin mouse monoclonal antibody (anti-Dig) as a model, to rationally initiate the hybridization chain reaction (HCR) for enzyme-free signal amplification. As a proof-of-concept, both a fluorophore Cy3-labeled reporter hairpin (RH) in the 3′ terminus and a single-stranded helper DNA (HS) were individually hybridized with a recognition single-stranded DNA (RS) modified with Dig hapten, while the unpaired loop of RH was hybridized with the exposed 3′-toehold of HS, isothermally self-assembling an intermediate metastable DNA structure. The introduction of target anti-Dig drove the concurrent conjugation with two tethered Dig haptens, powering the directional switch of this DNA structure into a stable conformation. In this case, the unlocked 3′-stem of RH was implemented to unfold the 5′-stem of the BHQ-2-labeled quench hairpin (QH), rationally initiating the HCR between them by the overlapping complementary hybridization. As a result, numerous pairs of Cy3 and BHQ-2 in the formed long double helix were located in spatial proximity. In response to this, the significant quenching of the fluorescence intensity of Cy3 by BHQ-2 was dependent on the variable concentration of anti-Dig, achieving a highly sensitive quantification down to the picomolar level based on a simplified protocol integrated with enzyme-free amplification.

Graphical abstract: Antibody-powered DNA switches to initiate the hybridization chain reaction for the amplified fluorescence immunoassay

Supplementary files

Article information

Article type
Paper
Submitted
14 jun. 2021
Accepted
09 jul. 2021
First published
12 jul. 2021

Analyst, 2021,146, 5067-5073

Antibody-powered DNA switches to initiate the hybridization chain reaction for the amplified fluorescence immunoassay

J. He, Z. Chen, H. Deng, R. Yuan and W. Xu, Analyst, 2021, 146, 5067 DOI: 10.1039/D1AN01045J

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