Chiral biosensing using terahertz twisted chiral metamaterial

Subwavelength chiral metamaterials with tunable geometries and compositions are essential to advance the development of chiral biochemical samples detection. Here, we report a spatial symmetry breaking chiral terahertz (THz) metamaterial structure with stacked layers of L-shape arranged gold disks as the periodic unit cell. The chiroptical response can be adjusted on-demand by manipulating the number of stacking layers and the twisted angle of the periodic unit between adjacent array layers. We reveal that the chiroptical response originates from the optical resonances of the gold disks and the adjacent gold disks array layers via experiments and numerical simulation analysis. Furthermore, we find that this chiral metamaterial can realize label-free detection of proline in biological samples and label-free enantio-discrimination of chiral molecules. The change of the analyte concentration can also regulate the transmission circular dichroism (TCD) intensity of the chiral metamaterials. Our results not only provide new ideas into the design of functional chiral metamaterials, but also bring new strategies to develop chiroptical biosensing devices. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

This paper reports a subwavelength chiral metamaterial structure with tunable geometries and compositions for chiral biochemical sample detection. The chiroptical response of the metamaterial can be adjusted by manipulating the number of stacking layers and the twisted angle of the periodic unit. Experimental and numerical analysis reveal that the chiroptical response originates from the optical resonances of the gold disks and the adjacent array layers. The chiral metamaterial can achieve label-free detection of proline in biological samples and enantio-discrimination of chiral molecules, and the transmission circular dichroism (TCD) intensity can be regulated by the analyte concentration.