Hydrodynamic Selection of Polymorphic Assembly Pathways in Plant Protein Amyloid Fibrils

Plant protein amyloid fibrils are universally assembled in liquid environments, yet their formation is often analyzed without explicitly considering the role of fluid motion. In practice, as a typical model system, soy protein amyloid fibrils (SAFs) are generated under dynamic hydrodynamic conditions involving shear and vortex transport. How such flow fields regulate fibril growth pathways and give rise to polymorphic assembly remains largely unexplored. Here, we elucidate the hydrodynamic selection of SAFs assembly pathways through nanoscale structural characterization combined with flow-field analysis. Atomic force microscopy (AFM) identifies six distinct fibril morphologies, including short-curved, javelin-like, loop-like, twisted ribbon, helical ribbon, and rod-like structures. By integrating AFM observations with particle image velocimetry (PIV) results, we propose a drafting, kissing, and docking (DKD) dynamic as a plausible hydrodynamic model for understanding polymorphic fibril assembly. Computational fluid dynamics (CFD) simulations further reproduce key characteristics of the experimentally observed flow fields and provide hydrodynamic support for the proposed interpretation of fibrillation pathways. These results demonstrate that an in-depth understanding of hydrodynamic selection behavior in polymorphic assembly pathways is important to pave the way for production of tailormade amyloid materials.