- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Enzyme-free fluorometric assay for chloramphenicol based on double stirring bar-assisted dual signal amplification
摘要： An enzyme-free fluorometric assay is described that accomplishes dual signal amplification by making use of a two stirring bars. Two Y-shaped DNA probes were designed and placed on the bars. When the target (with chloramphenicol as model analyte) is added, it triggers target recycling and simultaneously catalyzes hairpin assembly (CHA). A large fraction of DNA primers is released by the analyte from the bar to the supernatant and open hairpins with G-quadruplex DNA sequence. The G-quadruplex can specifically bind thioflavin T (ThT) to emit fluorescence (with excitation/emission maxima at 445 and 485 nm) for quantification of chloramphenicol. An enzyme is not needed. ThT is added to the system as a fluorescent DNA probe. All this strongly reduces the cost for sensor construction and usage. The dual signal amplification steps occur simultaneously which reduces the detection time. The assay was successfully employed to the determination of CAP in spiked milk and fish samples within 60 min and with a 16 pM limit of detection (at S/N = 3).
关键词： Food safety,Antibiotics detection,Thioflavin T,Catalyzed hairpin assembly,Target recycling
更新于2025-11-19 16:46:39
-
G-quadruplex specific dye-based ratiometric FRET aptasensor for robust and ultrafast detection of toxin
摘要： G-quadruplex specific dyes are powerful tools for probing nucleic acid structures. Among nucleic acids, aptamers are of great interest, and widely exploited to construct versatile bioassays. Herein, based on G-quadruplex selective dye, thioflavin T (ThT), for probing the intrinsic structure of aptamers, we proposed a ratiometric fluorescence resonance energy transfer (FRET) aptasensor enabling robust and ultrafast detection of toxin. The binding of target ochratoxin A (OTA) would destruct the G-quadruplex structure of aptamer. It would lead to the detachment of ThT dye from aptamer which diminished the FRET effect between ThT and terminal-labeled dye, thus allowing quantification of OTA via FRET signals. The FRET aptasensor would confer an enhancement of 76.9% of signal to background ratio compared to the ThT-based non-FRET aptasensor. Remarkably, the FRET mechanism would eliminate the signal fluctuation resulted from varied probe concentration, thus benefiting the robustness of the assay. The aptasensor could achieve a detection of limit of 0.38 ng/mL for OTA detection. And the detection of OTA could be finished within 30 s. Besides, the assay was successful in analyzing OTA in coffee and oat samples with recoveries rate of 93.93%–107.59%. Therefore, G-quadruplex specific dye-based probing and FRET method would be a compelling design strategy for aptasensor, and may facilitate their practical application in food safety and environmental screening.
关键词： Fluorescence resonance energy transfer,G-quadruplex specific dyes,Homogeneous analysis,Toxin,Thioflavin T,Aptamer
更新于2025-09-23 15:23:52
-
An ultrafast molecular rotor based fluorescent turn-on sensor for perrhenate anion in aqueous solution
摘要： Devising sensors for perrhenate anion in aqueous media is extremely challenging, and is seldom reported in literature. Herein, we report a fluorescence turn-on sensor for perrhenate anion in aqueous medium based on the aggregation induced emission of a popular ultrafast molecular rotor dye, Thioflavin-T. The selective response towards perrhenate anion has been rationalized in terms of matching water affinity, where the weakly hydrated perrhenate anion spontaneously forms a contact ion-pair with the weakly hydrated ultrafast molecule rotor based organic cation, Thioflavin-T, which in turn leads to an aggregate assembly that provides a fluorescence turn-on response towards perrhenate. The sensing response of Thioflavin-T is found to be quite selective towards perrhenate anion, when tested against the anions which are ubiquitously present in the environment such as chloride, nitrate, sulphate etc. The formation of self-assembled Thioflavin-T aggregates has been also investigated by time-resolved emission and temperature dependent measurements.
关键词： Aggregation induced emission,Turn-on sensor,Fluorescence sensor,Thioflavin-T,Perrhenate anion
更新于2025-09-10 09:29:36
-
Polymorph-specific distribution of binding sites determines thioflavin-T fluorescence intensity in α-synuclein fibrils
摘要： Thioflavin-T (ThT) is the most commonly used fluorescent dye for following amyloid formation semi-quantitatively in vitro, specifically probing the fibrillar cross-b-sheet content. In recent years, structural polymorphism of amyloid fibrils has been shown to be an important aspect of amyloid formation, both in vitro and in neurodegenerative diseases. Therefore, understanding ThT–amyloid interactions in the context of structural polymorphism of amyloids is necessary for correct interpretation of ThT fluorescence data. Here we study the influence of fibril morphology on ThT fluorescence and ThT binding sites, with two morphologically distinct but chemically identical a-synuclein polymorphs. In ThT fluorescence assays the two polymorphs show type-specific fluorescence intensity behaviour although their b-sheet content has been shown to be similar. Further, fluorescence lifetime measurements of fibril-bound ThT reveal the presence of at least two qualitatively different ThT binding sites on the polymorphs. The relative distributions of the binding sites on the fibril surfaces appear to be morphology dependent, thus determining the observed polymorph-specific ThT fluorescence intensities. These results, highlighting the role of fibril morphology in ThT-based amyloid studies, underline the relevance of polymorphs in ThT–amyloid interaction and can explain the variability often observed in ThT amyloid binding assays.
关键词： thioflavin-T,polymorphism,Amyloid,atomic force microscopy,a-synuclein
更新于2025-09-04 15:30:14