A robust yet simple method to generate fluorescent amyloid nanofibers

Covalent tagging of fluorophores is central to the mechanistic understanding of important biological processes including protein-protein interaction and protein aggregation. Hence, studies on fluorophore-tagged peptides help in elucidating the molecular mechanism of amyloidogenesis, its cellular internalization, and crosstalk potential. Despite the many advantages the covalently tagged proteins offer, difficulties such as expensive and tedious synthesis and purification protocols have become a matter of concern. Importantly, covalently tagged fluorophores could introduce structural constraints, which may influence the conformation of the monomeric and aggregated forms of proteins. Here, we describe a robust-yet-simple method to make fluorescent-amyloid nanofibers through a coassembly-reaction route that does not alter the aggregation kinetics and the characteristic & beta;-sheet-conformers of resultant nanofibers. Fluorescent amyloid nanofibers derived from insulin, lysozyme, A & beta;1-42, and metabolites were successfully fabricated in our study. Importantly, the incorporated fluorophores exhibited remarkable stability, remaining intact without leaching even after undergoing serial dilutions and prolonged storage periods. This method enables monitoring of cellular internalization of the fluorescent-amyloid-nanofibers and the detection of FRET-signals during interfibrillar interactions. This simple and affordable protocol may significantly help amyloid researchers working on both in vitro and animal models. This work illustrates a new method for preparing fluorescent amyloid nanofibers. The strategic fabrication mentioned in the study is highly relevant to the advancement of both fundamental and applied research in biological and materials sciences.

Automated summary

Covalent tagging of fluorophores is crucial for studying biological processes and has advantages despite challenges in synthesis and purification. A novel method for making fluorescent amyloid nanofibers is described, which maintains the characteristics of the nanofibers and exhibits stability. This method has significant implications for amyloid research in vitro and in animal models.