Thioflavin T─a Reporter of Microviscosity in Protein Aggregation Process: The Study Case of α-Synuclein.

Thioflavin T (ThT) informed microviscosity changes can be used to monitor protein aggregation. Steady-state, time-resolved and lasing spectroscopy were used to detect transient states in α-synuclein - a protein associated with Parkinson's disease. The major focus was on the nucleation phase, where conventional ThT fluorescence assay lacks appropriate sensitivity to detect early stage oligomers. Instead, lasing spectroscopy and lasing threshold parameters, in particular, were sensitive to detecting protein oligomers. Through lasing spectroscopy, a change in microviscosity correlating with the stages of protein aggregation was observed at two wavelengths 405 and 440 nm. The two wavelengths are associated with free dye molecules and β-sheet bound ThT molecules. This provides a perspective on elucidating the early formed protein aggregation, a critical aspect in understanding the pathogenesis of neurodegenerative diseases. The insights from the presented study shows the potential of using lasing spectroscopy as a sensitive tool in studying protein aggregation dynamics.