Plasmonic Toroidal Metamolecules Assembled by DNA Origami.

Area of Science:

• Plasmonics
• Metamaterials
• Chiroptics
• Nanoscale assembly

Background:

• Plasmonic metamolecules offer tunable optical properties.
• Chiroptical responses are crucial for sensing and advanced optical applications.
• Hierarchical assembly provides a route to complex nanostructures.

Purpose of the Study:

• To demonstrate hierarchical assembly of plasmonic toroidal metamolecules.
• To investigate their chiroptical properties in the visible spectrum.
• To explore their potential for chiral sensing platforms.

Main Methods:

• Hierarchical self-assembly of origami-templated helical building blocks.
• Fabrication of toroidal metamolecules.
• Optical characterization including circular dichroism spectroscopy.
• Theoretical simulations for validation.
• Spin-coating for orientation-dependent measurements.

Main Results:

• Successfully assembled toroidal metamolecules with tailored optical activity.
• Observed significantly stronger chiroptical responses compared to monomers and dimers.
• Demonstrated opposite circular dichroism spectra for enantiomers.
• Revealed distinct axial chiroptical responses through substrate alignment.
• Experimental data showed excellent agreement with theoretical predictions.

Conclusions:

• Hierarchical assembly is an effective strategy for creating plasmonic chiral nanostructures.
• Toroidal metamolecules exhibit enhanced and tunable chiroptical properties.
• These structures represent a promising platform for advanced chiral sensing applications.