Deciphering amyloid fibril molecular maturation through FLIM-phasor analysis of thioflavin T

The investigation of amyloid fibril formation is paramount for advancing our understanding of neurodegenerative diseases and for exploring potential correlated therapeutic strategies. Moreover, the self-assembling properties of amyloid fibrils show promise for the development of advanced protein-based biomaterials. Among the methods employed to monitor protein aggregation processes, fluorescence has emerged as a powerful tool. Its exceptional sensitivity enables the detection of early-stage aggregation events that are otherwise challenging to observe. This research underscores the pivotal role of fluorescence analysis, particularly in investigating the aggregation processes of hen egg white lysozyme, a model protein extensively studied for insights into amyloid fibril formation. By combining classical spectroscopies with fluorescence microscopy and by exploiting the fluorescence properties (intensity and lifetime) of the thioflavin T, we were able to noninvasively monitor key and complex molecular aspects of the process. Intriguingly, the fluorescence lifetime imaging-phasor analysis of thioflavin T fluorescence lifetime on structures at different stages of aggregation allowed to decipher the complex fluorescence decay behavior, highlighting that their changes rise from the combination of specific binding to amyloid typical cross-β structures and of the rigidity of the molecular environment.