Thioflavin T (ThT)

Thioflavin T is a benzothiazole salt obtained by the methylation of dehydrothiotoluidine with methanol in the presence of hydrochloric acid. Thioflavin T fluorescence is often used as a diagnostic of amyloid structure, but it is not perfectly specific for amyloid. Depending on the particular protein and experimental conditions, Thioflavin T may or may not undergo a spectroscopic change upon binding to precursor monomers, small oligomers, unaggregated material with a high beta sheet content, or even alpha helix-rich proteins. Conversely, some amyloid fibers do not affect Thioflavin T fluorescence, raising the prospect of false negative results. When it binds to beta sheet-rich structures, such as those in amyloid aggregates, the dye displays enhanced fluorescence and a characteristic red shift of its emission spectrum.