Engineering Chiroptical Interactions through Integrating Plasmonic Arrays with Cholesteric Nanocellulose.

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.