Target-triggered three-way junction in conjugation with catalytic concatemers-functionalized nanocomposites provides a highly sensitive colorimetric method for miR-21 detection.
Biosens Bioelectron 2018;
117:567-574. [PMID:
30005375 DOI:
10.1016/j.bios.2018.06.051]
[Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 06/22/2018] [Accepted: 06/26/2018] [Indexed: 12/20/2022]
Abstract
With the great advances in DNA nanotechnology, scientists have shown interest in developing dynamic nanostructures for theranostic applications, analyte sensing and cargo delivery. Here, we present a specific enzyme-free ultrasensitive platform based on a multilayer coupled signal amplification strategy to quantify miR-21 molecule. The biosensor was integrated based on three signal amplification gadgets, namely a translator-mediated catalytic hairpin assembly (CHA), a multilayer DNA concatemer on the surface of gold decorated magnetic nanoparticle (GMNP), and a DNAzyme-mediated catalytic signal amplification. MiR-21 mediates the release of a DNA translator from an immobilized duplex to engage in a CHA reaction using three hairpins, including a GMNP-conjugated hairpin 1 (H1), biotin-labeled hairpin 2 (H2) and a GMNP-conjugated hairpin 3 (H3) to form a three-way junction (3WJ). Meanwhile, a plenty of initiator strand 0 (S0) on GMNPs - each of which has been bifunctionalized with S0/H1 or S0/H3 - drive several multilayer peroxidase-mimicking DNAzyme concatemers in the presence of two accessory oligonucleotides; strand 1 (S1) and strand 2 (S2). Since a G-rich sequence was attached at the 5'-end of S1 strand, in the presence of hemin cofactor, an active G-quadruplex DNAzyme with peroxidase activity was formed. The concatemers on the surface of GMNPs can convert a colorless substrate to a green product. The biosensor can detect as low as 1 aM of miR-21 and provide an excellent capability to discriminate single-base mismatches. The required time for the formulation of the assay reagents is about three days and the reaction time for the detection of miR-21 takes place in less than four hours.
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