Chiral fingerprints in the visible regime with high sensitivity to the surrounding dielectric environment are highly desirable for nanophotonic applications, including ultrasensitive biosensing, enantioselective detection, and compact photonic devices. One common strategy to achieve such responses involves assembling gold nanorods (AuNRs) into chiral geometries, often using DNA origami scaffolds. Owing to their unique anisotropy, AuNRs exhibit both longitudinal and transverse dipolar plasmon modes in the near-infrared (NIR) and visible regions, respectively. However, the transverse mode, despite lying in the visible spectrum, exhibits weak sensitivity to environmental and morphological changes, thereby limiting its utility in nanophotonic systems. Here, using electromagnetic simulations, we demonstrate that AuNRs as short as ∼123 nm enable the selective excitation of higher-order plasmonic modes. These modes display strong optical and chiroptical responses in the visible regime, together with significantly enhanced refractive-index sensitivity compared with the strongly broadened transverse modes. Our findings have potential applications in the development of chirality-based biosensors and in facilitating nonlinear processes such as second-harmonic generation.
Sottie et al. (Wed,) studied this question.