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.

Thioflavin T: A versatile optical probe for chemo and biosensing

“…Liu et al developed a Forster resonance energy transfer (FRET) based label free fluorescent sensor for detection of thrombin (Liu et al, 2015). The sensor system comprised of a conjugated polymer (CP) as energy donor while ThT as energy acceptor.…”

“…Due to steric hindrance of thrombin, a long distance between the donor and acceptor exists, and hence a weak FRET signal is observed. Importantly, this sensor system allows rapid and sensitive detection of thrombin not only in aqueous solution but also in serum samples and hence presenting its potential utility in practical applications (Liu et al, 2015).…”

Magnetic chitosan/graphene oxide composite loaded with novel photosensitizer for enhanced photodynamic therapy

“…The novel photosensitizer HNPa as an anti-tumor drug model was then loaded onto the surface of the MCGO nanohybrid via p-p stacking and hydrogen bonding. 35 The composite MCGO-HNPa was comprehensively characterized by various methods. Cellular experiments in vitro were conducted to evaluate the potential of the novel photosensitizer HNPa as an anti-tumor drug in PDT and MCGO as an expected magnetic targeting delivery system that can transport anticancer drugs to tumor cells effectively.…”

Thrombin-Activatable Microbubbles as Potential Ultrasound Contrast Agents for the Detection of Acute Thrombosis

“…Several reports of thrombin-sensitive imaging probes for biomedical imaging using fluorescence 25,33–36 and magnetic resonance imaging 37 have been published recently. One example of a thrombin-sensitive US contrast agent has been reported.…”