Effects of Modifying Thioflavin T at the N3-Position on Its G4 Binding and Fluorescence Emission

Abstract

We previously synthesized thioflavin T (ThT) with a hydroxyethyl group introduced at the N3-position (ThT-HE), which binds predominantly to the parallel G-quadruplex (G4) structure found in c-Myc and emits strong fluorescence. In this study, to investigate the effects of introduced substituents on G4 binding and fluorescence emission, a ThT derivative in which the hydroxyl group of ThT-HE was replaced with an amino group (ThT-AE) was synthesized for the first time. Furthermore, three other N3-modified ThT derivatives (ThT-OE2, ThT-SP, and ThT-OE11) having different substituent structures were synthesized by the N-acylation of the terminal amino group of ThT-AE, and their G4-binding and emission properties were investigated. The results showed that, although ThT-AE shows binding selectivity depending on the type of G4, its emission intensity is significantly decreased as compared to that of ThT-HE. However, ThT-OE11, which features an 11-unit oxyethylene chain attached to the terminal amino group of ThT-AE, regained about one-half of the emission intensity of ThT-HE while retaining selectivity for G4s. Accordingly, ThT-OE11 may be used as a key intermediate for synthesizing the conjugates of G4 binders and probes.

Thioflavin-modified molecularly imprinted hydrogel for fluorescent-based non-enzymatic glucose detection in wound exudate

“…Aiming to maximize Tht rotation in response to nearly imperceptible environmental variations, we settled on simply entrapping physically free Tht into the rigid matrix of the hydrogel. Thanks to this expedient, we were able to convert minimal changes of stiffness into a measurable signal given the glitches in the fluorescence variation of Tht observed when it is conjugated [ 38 ] or chemically modified [ 39 ]. With a mechanically rigid matrix, we limited the swelling and the variation of the internal structure of the hydrogel which could lead to an undesired oscillation of Tht's fluorescence regardless of glucose.…”