[1] 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.

Quenching effects of the nearby excitation peak at 450 nm is suspected to play a role in minimizing emissions.

However, when thioflavin T binds to amyloid fibrils, the two rotational planes of the two rings become immobilized and therefore, this molecule can maintain its excited state.

Conversely, some amyloid fibers do not affect thioflavin T fluorescence,[11] raising the prospect of false negative results.

[5] This latter characteristic of thioflavin S results in high background fluorescence, making it unable to be used in quantitative measurements of fibril solutions.