Figure 4: Monolayer chiral sample measurements.

(a) Measured monolayer protein (Concanavalin A prepared with 1 mg ml⁻¹ concentration) on ±60° metamaterials (MTM). The solid black (red) squares (circles) refer to measurements from the +60° metamaterials (with proteins), the void black (red) squares (circles) refer to that from the −60° metamaterials (with proteins), and the grey straight line indicates 0 degree CD for guide-to-the-eye. The CD summation of the protein (blue diamonds) shows a negative bend, indicating the overall ‘right-handedness’ of the analyte. For a large protein with different chiral centers, the CD signal is more complicated, and may show spectral oscillations with changing signs. Our results are consistent with chirality assignment based on conventional CD measurements. The error bars indicates standard deviation from three repeated measurements for each analyte across different locations on the metamaterials. The legend ‘MTM w/P’ denotes the metamaterials with proteins. (b) CD measurements of a chiral anticancer drug (Irinotecan hydrochloride at a concentration of 1 mg ml⁻¹) on metamaterials. Its CD summation (blue diamonds) with the same pair of metamaterials shows positive bend, indicating its overall ‘left-handedness’. The black curves were measurements from the ±60° metamaterials with water, and the grey straight line indicates 0 degree CD for guide-to-the-eye. The error bars indicates standard deviation from three repeated measurements for each analyte across different locations on the metamaterials. The legend ‘MTM w/w’ denotes the metamaterials with water; ‘MTM w/D’ denotes the metamaterials with the chiral drug. The inset indicates that this measurement is conducted in a flow-cell setting.