Thioflavin T and Its Photoirradiative Derivatives: Exploring Their Spectroscopic Properties in the Absence and Presence of Amyloid Fibrils

Abstract

In this work, we found that, during storage or after UV irradiation, ThT is demethylated or oxidized, forming three derivatives. These three derivatives were purified by high performance liquid chromatography and characterized by mass and nuclear magnetic resonance spectroscopy and the spectroscopic properties of pure ThT and the derivatives carefully compared. Our results show that the emission peak at 450 nm results from oxidized ThT and not from the monomeric form of ThT, as previously proposed. The partial conversion of ThT into oxidized and demethylated derivatives has an effect on amyloid detection using ThT assay. Irradiated ThT has the same lag time as pure ThT in the amyloidogenesis of insulin, but the intensity of the emitted fluorescence is significantly decreased.

Enhanced two-photon absorption and fluorescence upconversion in Thioflavin T micelle-type aggregates in glycerol/water solution

“…Specifically, dThT-1 is responsible for the emission observed at approximately 450 nm when excited at 340 nm. Emission is not observed in pure ThT, dThT-2, and dThT-3 unless the molecules are bound to amyloid fibrils [37].…”

“…Interesting to note is the poor overlap between excitation and absorption. Chen and coworkers attribute this effect to a degradation of pure ThT into three kinds of derivatives (dThT-1, dThT-2, and dThT-3) after storage or by UV irradiation [37]. Specifically, dThT-1 is responsible for the emission observed at approximately 450 nm when excited at 340 nm.…”

Multiphase Protein Microgels

“…The localisation of the lysozyme protein inside the microgels was visualised by exploiting increased quantum yield and red‐shifted fluorescence of the dye Thioflavin‐T (ThT) upon binding to amyloid fibrils (See Methods) followed by examination using confocal microscopy (Figure c). A striking difference in the localization of the fluorescent signal was observed between lysozyme microgels (Figure c(i)), dextran‐lysozyme microgels (Figure c(ii)) and PEG‐lysozyme microgels (Figure c(iii)).…”

An ultrafast molecular rotor based ternary complex in a nanocavity: a potential “turn on” fluorescence sensor for the hydrocarbon chain

“…ThT was recrystallized from double distilled water. Its purity was checked through absorption, 39 emission, 39 and proton NMR spectroscopy. 40 g-CD was purchased from TCI, India, and used without further purification.…”