Circular Dichroism Enhancement and Biosensing Application of Composite Dielectric Chiral Nanostructures

Chiral nanostructures with strong circular dichroism (CD) have been widely used in molecular detection, chemical analysis, and biosensing. However, how to enhance and dynamically adjust the CD signal of the chiral nanostructures is still a current challenge. Here, monolayer molybdic sulfide (MoS2) is introduced into the composite dielectric chiral nanostructures (CDCNs) composed of silicon–vanadium dioxide Z-shaped nanorods placed on the silica–silver substrate to enhance and dynamically adjust the CD signal. Results demonstrate that the coupling between CDCNs and MoS2 results in different absorption enhancing under different circularly polarized lights and strong CD effects. The surface electric field distribution of CDCNs/MoS2 reveals that the three CD signals are mainly due to the surface plasmon polariton on the surface of the silver and the guided mode resonance in silica along the x or y directions, respectively. The CD signals can be actively adjusted through the insulator–metal transition of vanadium dioxide. In addition, the coupling characteristics between different chiral molecules and CDCNs/MoS2 can be applied in the identification of chiral molecules. These results provide a new method for enhancing and dynamically adjusting CD signals and will promote the sensing of chiral molecules.