G-quadruplex-bridged triple-helix aptamer probe strategy: A label-free chemiluminescence biosensor for ochratoxin A

• Published in: Sensors and actuators. B, Chemical Chemical, 2019-11, Vol.298, p.126867, Article 126867
• Main Authors: Wang, Yonghong, Fang, Zeyang, Ning, Ge, Mao, Shaoming, Wu, Yaohui, Wu, Shun, Liu, Gao-Qiang
• Format: Article
• Language: English
• Subjects: Biosensors; Chemiluminescence; Dependence; G-quadruplex; Hydrogen peroxide; Label-free; Ochratoxin A; Organic chemistry; Redesign; Triple-helix aptamer probe
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2019.126867

[Display omitted] •A label-free and signal-on chemiluminescence strategy was presented to detect OTA.•A novel TAP switch was designed and the G-quadruplex-catalyzed luminol-H2O2 system was employed.•The structural transformation of the TAP switch was triggered by the OTA with signal probe released.•The signal probe bridged signal transduction possessing the virtue of universality.•The fabrication of TAP endowed the sensitivity and specificity of the assay. After successively introducing elements of a triple-helix aptamer probe (TAP) and a luminol–hydrogen peroxide (H2O2) solution, we proposed a brand-new chemiluminescence (CL)-based biosensor for the assay of ochratoxin A (OTA). Primarily, the TAP contains an aptamer loop, two DNA segment stems, and a triplex-forming oligonucleotide (signal probe). In the presence of a target, the aptamer sequence binds to the target with an impressive affinity. This association leads to a conformational change in the TAP, thus releasing the signal probe. Sequentially, with the participation of hemin and potassium ions, the dissociated probe forms into a G-quadruplex structure that is capable of catalyzing luminol to produce CL mediated by H2O2. In contrast, in the absence of the target, a low background signal remains. Using this approach of combining a novel TAP switch with a G-quadruplex-catalyzed luminol-H2O2 system, we presented a label-free and signal-on CL strategy for the measurement of OTA. Under optimal conditions, the gradually strengthened signal maintained a linear dependence on target concentrations ranging from 0.1 ng/mL to 2.0 ng/mL, and the detection limit was as low as 0.07 ng/mL. This newly designed, simple, and cost-effective protocol affords high sensitivity, specificity, suitability, and efficacy for biosensing. Thus, this protocol is attractive for a range of target quantifications, with only the matched aptamer requiring replacement (no redesign of signal probes).