Cysteine-encoded chirality evolution in plasmonic rhombic dodecahedral gold nanoparticles

Hye-Eun Lee,Jungho Mun,Hyo-Yong Ahn,Junsuk Rho,Yoon Young Lee,Ryeong Myeong Kim,Sang Won Im,Gi Hyun Byun,Ki Tae Nam

doi:10.1038/s41467-019-14117-x

Abstract

Chiral plasmonic nanostructures have opened up unprecedented opportunities in optical applications. We present chirality evolution in nanoparticles focusing on the crystallographic aspects and elucidate key parameters for chiral structure formation. From a detailed understanding of chirality formation, we achieved a morphology (432 Helicoid IV) of three-dimensionally controlled chiral plasmonic nanoparticles based on the rhombic dodecahedral shape. The role of the synthesis parameters, seed, cysteine, cetyltrimethylammonium bromide and ascorbic acid on chiral formation are studied, and based on this understanding, the systematic control of the chiral structure is presented. The relation between the modulated chiral structure factors and optical response is further elucidated by electromagnetic simulation. Importantly, a new optical response is achieved by assembling chiral nanoparticles into a film. This comprehensive study of chiral nanoparticles will provide valuable insight for the further development of diverse chiral plasmonic nanostructures with fascinating properties.

Highlights

Chiral plasmonic nanostructures have opened up unprecedented opportunities in optical applications
The change of the low-index nanoparticles from cube to octahedron led to another type of chiral-shaped nanoparticle, 432 helicoid III, which showed the highest g-factor of 0.2 in the visible range among the reported nanoparticles based on bottom-up synthesis methods
A new chiroptical response is created by assembling the particles on the substrate, based on the merits of the chirality developed in single nanoparticles and the high-density packing of nanoparticles

Summary

Introduction

Chiral plasmonic nanostructures have opened up unprecedented opportunities in optical applications. At the same time, during the transformation of seeds, the Cys molecules continuously attached to the gold surface and modified the growth direction via strong interaction, resulting in Cys-induced chiral nanoparticles. To understand the chiral development of 432 helicoid IV, time-dependent evolution of nanoparticles was observed by SEM and CD measurements at 5min intervals (Supplementary Fig. 5).

Results

Conclusion