Antibody-powered DNA switches to initiate the hybridization chain reaction for the amplified fluorescence immunoassay. Issue 16 (23rd July 2021)

• Record Type: Journal Article
• Authors: He, Jia-Yang; Chen, Ze-Hui; Deng, Hui-Lin; Yuan, Ruo; Xu, Wen-Ju
• Is Part Of: Analyst. Volume 146:Issue 16(2021)
• Page Start: 5067
• Page End: 5073
• Publication Date: 2021-07-23
• Subjects: Chemistry, Analytic -- Periodicals; 543
• DOI: 10.1039/d1an01045j
• Languages: English
• ISSNs: 0003-2654

Abstract

Abstract : Targeted bivalent anti-Dig antibody as an input to power a directional switch of the DNA structure through a specific binding event with two tethered haptens, rationally integrating with the hybridization chain reaction for signal amplification. 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.