title: Thioflavin T as an Efficient G-Quadruplex Inducer for the Highly Sensitive Detection of Thrombin Using a New Föster Resonance Energy Transfer System.
abstract: We report a new Föster resonance energy transfer (FRET) system that uses a special dye, thioflavin T (ThT), as an energy acceptor and a water-soluble conjugated polymer (CP) with high fluorescence as an energy donor. A simple, label-free, and sensitive strategy for the detection of thrombin in buffer and in diluted serum was designed based on this new system using ThT as an efficient inducer of the G-quadruplex. The difference between the blank and the positive samples was amplified due to distinctive FRET signals because thrombin has little effect on the intercalation of ThT into the G-quadruplex. In the absence of the target, ThT induces the aptamer to form a G-quadruplex and intercalates into it with strong fluorescence. The electrostatic attractions between the negatively charged G-quadruplex and positively charged CP allow a short donor-acceptor distance, resulting in a high FRET signal. However, in the presence of the target, the aptamer forms a G-quadruplex-thrombin complex first, followed by the intercalation of ThT into the G-quadruplex. A long distance exists between the donor and acceptor due to the strong steric hindrance from the large-sized thrombin, which leads to a low FRET signal. Compared with previously reported strategies based on the FRET between the CP and dye, our strategy is label-free, and the sensitivity was improved by an order of magnitude. Our strategy also shows the advantages of being simple, rapid (about 50 min), sensitive, label-free, and low-cost in comparison to strategies based on the FRET between quantum dots and dyes.
authors.forename: Xingfen
authors.initials: X
authors.lastname: Liu
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: Hua
authors.forename: Quli
authors.initials: Q
authors.lastname: Fan
authors.forename: Jie
authors.initials: J
authors.lastname: Chao
authors.forename: Shao
authors.initials: S
authors.lastname: Su
authors.forename: Yan-Qin
authors.initials: YQ
authors.lastname: Huang
authors.forename: Lianhui
authors.initials: L
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
mesh_terms: D052160:Benzothiazoles; D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005456:Fluorescent Dyes / Q000737:chemistry; D054856:G-Quadruplexes; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013844:Thiazoles / Q000737:chemistry*; D013917:Thrombin / Q000032:analysis* / Q000737:chemistry
chemical_list: D052160:Benzothiazoles; D005456:Fluorescent Dyes; D013844:Thiazoles; C009462:thioflavin T; D004247:DNA; D013917:Thrombin
keywords: FRET; Föster resonance energy transfer; G-quadruplex; conjugated polymer; thioflavin T; thrombin