A Sensitive Fluorescent Assay for Tetracycline Detection Based on Triple-helix Aptamer Probe and Cyclodextrin Supramolec
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ORIGINAL ARTICLE
A Sensitive Fluorescent Assay for Tetracycline Detection Based on Triple-helix Aptamer Probe and Cyclodextrin Supramolecular Inclusion Hui He 1 & Chuchu Xie 1 & Liu Yao 1 & Ge Ning 2 & Yonghong Wang 1 Received: 8 September 2020 / Accepted: 5 October 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Herein, an effective pyrene excimer signaled fluorescent biosensor for the determination of tetracycline based on triple-helix aptamer probe (TAP) and supramolecular inclusion of cyclodextrin was reported. The TAP was devised containing an aptamer loop, two DNA segment stems and a triplex-forming oligonucleotide (signal probe) labeled with pyrenes at 5′ and 3′ ends. The presence of target could result in its binding towards aptamer with a mighty affinity, leading to a conformation change of the TAP and whereupon the release of the signal probe. This liberty of signal probe enabled the formation of pyrene excimer, generating fluorescence signals. Further, signal amplification was fulfilled through the addition of γ-cyclodextrin which could interact with pyrene dimer, thus leading to an enhanced “on-state” of the sensing ensemble. In contrast, when the target was absent, the sensing ensemble remained “off-state” because of the long distance between two pyrene molecules. When the conditions were properly optimized, the increasing signal kept a linear dependence on target concentrations ranging from 5.0 nM to 100 nM, and the detection limit reached as low as 1.6 nM. In this way, a newly-constructed, simple, and economically affordable protocol enjoys desirable efficiency, sensitivity, specificity in biosensing. Also, its universality as another attractive behalf in assaying diverse targets was envisioned with only the need of matched aptamer replacement. Keywords Tetracycline . Fluorescent . Biosensor . γ-cyclodextrin . Triple-helix aptamer probe
Introduction When researches on the double strand DNA became increasingly thorough, scientists were having their eyes on other structures of DNA sequences and their intriguing possibilities. Triple-helix aptamer probe (TAP) was born at certain expectation which could be formed autonomously relying on Watson-Crick and Hoogsteen base parings under optimized conditions [1, 2]. In structure of stem-loop, it was composed of an aptamer sequence, two arm-like DNA segments flanked Hui He and Chuchu Xie are co-first authors. * Yonghong Wang [email protected] 1
Hunan Provincial Key Laboratory for Forestry Biotechnology & International Cooperation Base of Science and Technology Innovation on Forest Resource Biotechnology, Central South University of Forestry and Technology, Changsha 410004, China
2
International Education Institute, Hunan University of Chinese Medicine, Changsha 410208, China
by sides and a triplex formed oligonucleotide. Apart from advantage of novelty, compared with routine double strand DNA, TAP were equally structurally stable but significantly sensitive and specific towards targets due to the affinity realized by the
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