Aluminum Nanoparticles with Hot Spots for Plasmon-Induced Circular Dichroism of Chiral Molecules in the UV Spectral Interval

TL;DR

This study demonstrates that aluminum nanoparticle dimers can significantly enhance circular dichroism signals of chiral biomolecules in the UV range, offering potential for improved chiral sensing in biomedical applications.

Contribution

The paper introduces the use of aluminum nanocrystals as plasmonic antennas for UV CD enhancement, which is more effective than traditional gold or silver systems for biomolecular sensing.

Findings

Al nanocrystals exhibit strong CD signals in the UV spectral region.

Al nanocrystals have better spectral overlap with biomolecular transitions than Au or Ag.

Potential applications in chiral biomolecule sensing and drug development.

Abstract

Plasmonic nanocrystals with hot spots are able to localize optical energy in small spaces. In such physical systems, near-field interactions between molecules and plasmons can become especially strong. This paper considers the case of a nanoparticle dimer and a chiral biomolecule. In our model, a chiral molecule is placed in the gap between two plasmonic nanoparticles, where the electromagnetic hot spot occurs. Since many important biomolecules have optical transitions in the UV, we consider the case of Aluminum nanoparticles, as they offer strong electromagnetic enhancements in the blue and UV spectral intervals. Our calculations show that the complex composed of a chiral molecule and an Al-dimer exhibits strong CD signals in the plasmonic spectral region. In contrast to the standard Au- and Ag-nanocrystals, the Al system may have a much better spectral overlap between the typical biomolecule's optical transitions and the nanocrystals' plasmonic band. Overall, we found that Al nanocrystals used as CD antennas exhibit unique properties as compared to other commonly studied plasmonic and dielectric materials. The plasmonic systems investigated in this study can be potentially used for sensing chirality of biomolecules, which is of interest in applications such as drug development.