Plasmonic Toroidal Metamolecules Assembled by DNA Origami

TL;DR

This paper reports the hierarchical assembly of plasmonic toroidal metamolecules using DNA origami, exhibiting enhanced optical activity and chiroptical responses suitable for chiral sensing applications.

Contribution

It introduces a novel DNA origami-based method to assemble plasmonic toroidal structures with tailored optical properties and demonstrates their chiroptical responses.

Findings

Stronger chiroptical response than monomers and dimers.

Opposite circular dichroism spectra for enantiomers.

Consistent experimental and theoretical results.

Abstract

We demonstrate hierarchical assembly of plasmonic toroidal metamolecules, which exhibit tailored optical activity in the visible spectral range. Each metamolecule consists of four identical origami-templated helical building blocks. Such toroidal metamolecules show stronger chiroptical response than monomers and dimers of the helical building blocks. Enantiomers of the plasmonic structures yield opposite circular dichroism spectra. The experimental results agree well with the theoretical simulations. We also demonstrate that given the circular symmetry of the structures, distinct chiroptical response along their axial orientation can be uncovered via simple spin-coating of the metamolecules on substrates. Our work provides a new strategy to create plasmonic chiral platforms with sophisticated nanoscale architectures for potential applications such as chiral sensing using chemically-based assembly systems.