# Engineering Chiroptical Interactions through Integrating Plasmonic Arrays with Cholesteric Nanocellulose

## TL;DR

Researchers created a new material combining gold nanoparticles and plant-based cellulose to control light in a chiral way, enabling tunable optical properties for advanced applications.

## Contribution

A scalable fabrication method for chiral plasmonic composites with tunable and strong chiroptical responses is introduced.

## Key findings

- The composite films exhibit strong plasmonic circular dichroism with a dissymmetry factor of –0.19 ± 0.02.
- The chiroptical response inverts upon reversing illumination direction, showing antisymmetric CD behavior.

## Abstract

Achieving scalable fabrication with precise control of chiroptical properties in chiral plasmonic materials remains challenging. We present a new family of engineered chiroptical composites comprising linearly assembled gold nanoparticle arrays integrated with cholesteric self‐assembled cellulose nanocrystals (CNCs). Aqueous CNC suspensions are cast onto pre‐assembled achiral plasmonic nanoparticle arrays via evaporation‐induced transfer imprinting lithography, yielding centimeter‐scale hybrid films with custom‐tailored chiroptical responses. During drying, CNCs co‐assemble with the gold nanoparticles at the interface, preserving the array's linear arrangement and keeping it isolated from the overlying cholesteric CNC layers. This configuration combines the linear dichroism of the plasmonic array with the linear birefringence of the CNC matrix, producing strong and tunable plasmonic circular dichroism at the surface lattice resonance, reaching 1217 ± 51 mdeg with a dissymmetry factor of –0.19 ± 0.02. Our approach provides a sustainable platform for engineering multifunctional chiral plasmonic materials with potential applications in optical sensing, photonic devices, and chiral biointerfaces.

In this study, we demonstrate how the combination of plant‐based cellulose and gold nanoparticle lines produces robust, tunable chiral light control in composite films. The resulting plasmonic cellulose composite exhibits a strong plasmonic CD at the surface lattice resonance, along with an inversion of chiroptical response upon reversing the illumination direction, revealing an antisymmetric CD behavior.