Chiral Plasmonic Nanoshells via Chitin Nanocrystals Templating

Liquid crystals are among the most fascinating states of soft matter, combining fluidity with long-range molecular organization. In nature, they play a pivotal role in the structural coloration of numerous biological systems, from butterfly wings to beetle exoskeletons, producing iridescent hues without pigments. This remarkable phenomenon originates from the self-assembly of cellulose or chitin nanocrystals, which spontaneously organize into helicoidal liquid crystalline phases capable of selectively reflecting light, giving rise to nature’s most vivid structural colors. Yet, the fundamental question remains: What drives this self-assembly? Despite extensive studies, the precise mechanism governing the transfer of chirality from the nanometric building blocks to the mesoscale remains unresolved. One prevailing hypothesis, known as the Twisted Raft Model, proposes that a minority population of nanocrystals—termed bundles—act as chiral dopants, dictating the macroscopic helical arrangement of the liquid crystal phase. However, the reason behind this behavior remains speculative. It is believed that these bundles possess an amplified chiral geometry compared to individual nanocrystals, enabling them to mediate the transfer of chirality across length scales. Here, scientific progress faces a critical roadblock: no existing analytical technique has demonstrated sufficient sensitivity to detect the extremely weak structural asymmetry of nanocrystals. This project aims to overcome this challenge by developing a novel plasmonic platform consisting of gold nanoshell superstructures grown on nanocrystal surfaces. These plasmonic architectures will serve as unprecedented tools for quantifying nanocrystal chirality with exceptional sensitivity. By leveraging their optical response, they will provide fundamental insights into the mechanisms governing liquid crystal self-assembly, enabling future studies to achieve a deeper understanding of how chirality propagates from the nanoscale to complex mesophases.