Confinement-Induced Liquid Crystalline Transitions and Chirality Inversion in Amyloid Fibril Cholesteric Tactoids

TL;DR

This study discovers cholesteric phases in amyloid fibrils, revealing confinement-induced transitions and chirality inversion, which enhances understanding of chiral liquid crystalline behavior in biological materials.

Contribution

It reports the first observation of cholesteric phases in amyloid fibrils and explains the chirality inversion through energy functional theory, expanding knowledge of chiral nematic phases.

Findings

Cholesteric phases found in amyloid fibrils after shear shortening.

Confinement induces transitions between nematic and cholesteric tactoids.

Chirality inversion from left-handed fibrils to right-handed cholesteric droplets.

Abstract

Chirality is ubiquitous in nature and plays crucial roles in biology, medicine, physics and materials science. Understanding and controlling chirality is therefore an important research challenge with broad implications in fundamental and applied sciences. Unlike other classes of chiral colloids, such as nanocellulose or filamentous viruses, amyloid fibrils form nematic phases but appear to miss their twisted form in the phase diagram, the so-called cholesteric or chiral nematic phases, and this despite a well-defined chirality at the single fibril level. Here we report the discovery of cholesteric phases in amyloid fibrils, by using \b{eta}-lactoglobulin fibrils suitably shortened by shear stresses. The physical behavior of this new class of cholesteric materials exhibits unprecedented structural complexity, with confinement-drivenordering transitions between at least three types of nematic and cholesteric tactoids. We use energy functional theory to rationalize these results and demonstrate a chirality inversion upon increasing hierarchical levels, from the left-handed amyloids to the right-handed cholesteric droplets. These findings significantly deepen our understanding of chiral nematic phases and may pave the way to their optimal use in soft nanotechnology, nanomaterials templating and self-assembly.