Controlled ligation and elongation of uniformly truncated amyloid nanofibrils.

This study investigates the production and inter-fibril interactions of uniformly truncated amyloid nanofibrils. By varying extrusion cycles (0, 50, and 100) and using carbonate filters with 100 nm and 200 nm pore sizes, precise fibril length control was achieved. Atomic force microscopy (AFM) confirmed that the mean length of the truncated fibrils corresponded to the respective pore size as extrusion cycles increased. AFM imaging combined with bicinchoninic acid assay analysis elucidated the mechanism underlying fibril truncation during extrusion. Subsequent incubation at 60 °C revealed that 200 nm-long fibrils assembled into denser structures than 100 nm-long fibrils, likely due to strain energy introduced during truncation, which appears to facilitate twisting during ligation and elongation between truncated fibrils. These findings advance understanding of the end-to-end elongation mechanisms of amyloid nanofibrils, shedding light on their structural dynamics and polymorphic properties.