Amplification of Molecular Chiroptical Effect by Low-loss Dielectric Nanoantennas

TL;DR

This study demonstrates that silicon nanostructures can significantly amplify molecular chiroptical signals through resonant excitation, outperforming gold-based nanoantennas and offering a low-damage approach for chiral sensing in biomedical applications.

Contribution

The paper introduces silicon-based dielectric nanoantennas as a superior, low-loss alternative to gold nanoantennas for amplifying molecular chiroptical effects, with potential biomedical applications.

Findings

Silicon nanoantennas produce larger CD signals than gold counterparts.

Resonant excitation enhances chiroptical responses in hybrid systems.

Silicon structures generate negligible photothermal effects, reducing thermal damage.

Abstract

We report here chiroptical amplification effect occurring in the hybrid systems consisting of chiral molecules and Si nanostructures. Under resonant excitation of circularly polarized light, the hybrid systems show strong CD induction signals at optical frequency, which arise from both the electric and magnetic responses of the Si nanostructures. More interestingly, the induced CD signals from Si-based dielectric nanoantennas are always larger than that from Au-based plasmonic counterparts. The related physical origin was disclosed. Furthermore, compared to the Au-based high-loss plasmonic nanoantenas, Si-based low-loss structures would generate negligible photothermal effect, which makes Si nanoantennas become an optimized candidate to amplify molecular CD signals with ultralow thermal damages. Our findings may provide a guideline for the design of novel chiral nanosensors for applications in the fields of biomedicine and pharmaceutics.