Thioflavin-T (ThT) is a widely used fluorescent dye for detecting and analyzing amyloid fibrils. When bound to amyloid fibrils, ThT undergoes a significant increase in fluorescence, making it a powerful tool for amyloid detection. Recent studies have elucidated the molecular mechanism of ThT binding to amyloid fibrils at an atomic level. These studies reveal that ThT binds to the cross-β structure of amyloid fibrils, which consists of β-sheets arranged in a specific pattern. ThT binds to channels formed by cross-strand ladders on the β-sheet surface, leading to a dramatic increase in fluorescence. The binding of ThT is influenced by the structural features of the fibrils, including the arrangement of side-chains and the presence of aromatic residues. ThT's binding is also affected by factors such as the pH and ionic strength of the solution. The findings from these studies provide insights into the structural properties of amyloid fibrils and have implications for the development of new amyloid diagnostics, inhibitors, and therapeutics. The understanding of ThT binding mechanisms is crucial for interpreting ThT staining results and for designing more effective amyloid-related diagnostic tools.Thioflavin-T (ThT) is a widely used fluorescent dye for detecting and analyzing amyloid fibrils. When bound to amyloid fibrils, ThT undergoes a significant increase in fluorescence, making it a powerful tool for amyloid detection. Recent studies have elucidated the molecular mechanism of ThT binding to amyloid fibrils at an atomic level. These studies reveal that ThT binds to the cross-β structure of amyloid fibrils, which consists of β-sheets arranged in a specific pattern. ThT binds to channels formed by cross-strand ladders on the β-sheet surface, leading to a dramatic increase in fluorescence. The binding of ThT is influenced by the structural features of the fibrils, including the arrangement of side-chains and the presence of aromatic residues. ThT's binding is also affected by factors such as the pH and ionic strength of the solution. The findings from these studies provide insights into the structural properties of amyloid fibrils and have implications for the development of new amyloid diagnostics, inhibitors, and therapeutics. The understanding of ThT binding mechanisms is crucial for interpreting ThT staining results and for designing more effective amyloid-related diagnostic tools.