Abstract
A terahertz (THz) all-dielectric metasurface with crescent cylinder arrays for chiral drug sensing has been demonstrated. Through the multipole expansion method, we theoretically found that breaking the symmetry of the metasurface can excite higher-order resonance modes and provide stronger anisotropy as well as enhanced sensitivity for the surroundings, which gives a better sensing performance than lower-order resonance. Based on the frequency shift and transmittance at higher-order resonance, we carried out the sensing experiments on (R)-(−)-ibuprofen and (S)-(+)-ibuprofen solution on the surface of this metasurface sensor. We were able to monitor the concentrations of ibuprofen solutions, and the maximum sensitivity reached 60.42 GHz/mg. Furthermore, we successfully distinguished different chiral molecules such as (R)-(−)-ibuprofen and (S)-(+)-ibuprofen in the 5 μL trace amount of samples. The maximum differentiation was 18.75 GHz/mg. Our analysis confirms the applicability of this crescent all-dielectric metasurface to enhanced sensing and detection of chiral molecules, which provides new paths for the identification of biomolecules in a trace amount.
Highlights
Alexander Shkurinov and Chao LiWith increasing demands for developing reliable and effective biological sensors [1], terahertz (THz) radiation has attracted great attention as a promising tool in biological and medical investigation in recent years
(EQ and MQ modes) and lower-order resonance (ED and magnetic dipolar (MD) modes), which have differAs shown in Figure 1d, a femtosecond laser with a wavelength of 800 nm is incident on ent electric and magnetic antenna field distributions from the bound statesTHz in the continuum in a GaAs photoconductive which emits a linearly polarized pulse
Wang’s work, so the two structures show different responses to changes in the surroundis focused on the sensor filled with ibuprofen solutions
Summary
With increasing demands for developing reliable and effective biological sensors [1], terahertz (THz) radiation has attracted great attention as a promising tool in biological and medical investigation in recent years. Ibuprofen (4-isobutyl-2-phenylpropionic acid, C13 H18 O2 ), a well-known painkiller and an efficient anti-inflammatory, is widely used in daily life It contains in its chemical structure a stereogenic carbon, and, it has two enantiomers, called S-(+)-ibuprofen and R-(−)-ibuprofen, respectively. Asgari Somayyeh’s group [25] proposed a tunable and controllable graphene chiral metastructure to analyze the collagen biomolecule Their simulations showed that a refractive index sensitivity value can be achieved as high as 0.96 THz per refractive index unit for the CD spectra. The experimental results show that our metasurface-based sensor is compatible with drug concentration detection and chiral biomolecule recognition
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