High Sensitivity and Label-Free Detection of the SARS-CoV-2 S1 Protein Using a Terahertz Meta-Biosensor

Abstract

High sensitivity and quantitative detection of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein (S protein) is of great significance for the diagnosis and treatment of coronaviruses. Here, we utilized terahertz time-domain spectroscopy (THz-TDS) integrated with a metamaterial (MM)-based biosensor and biological modification technology to demonstrate a high accuracy and label-free detection of the SARS-CoV-2 S1 protein by comparing the changes of the dielectric environment before and after binding the S1 protein. To confirm the sensing characteristics observed in the experiments and provide a further insight into the sensing mechanisms, we performed numerical simulations through varying the thickness, quantity, position, and refractive index of analyte aggregates. The sensitivity increases with the increase of the number of gaps and the amount of analyte near the gaps, which convincingly proves that the frequency shift and sensing performance are strongly influenced by the field enhancement and near-field coupling at the gap area.

A terahertz metasurface biosensor based on electromagnetically induced transparency for fingerprint trace detection

“…In the measurement, a homemade THz time-domain spectroscopy (THz-TDS) system with a frequency range of 0.1-3 THz was used to obtain THz temporal waveforms and transmission spectra. 20,21 Here, THz signals through the blank quartz substrate and metasurface biosensor with or without analyte were measured to serve as reference and sample signals, respectively. Then, the amplitude transmission was given by T(o) = E sam (o)/E ref (o), where E sam (o) and E ref (o) are corresponding fast Fourier transform (FFT) spectra of the time-domain sample and reference signals, respectively.…”

Metasurface-Assisted Terahertz Sensing

“…It was similar to ref. [48], but the height of the inner triadius was not fixed. Meanwhile, Yang et al, from the same group, also published a similar structure [112], consisting of two concentric split-ring resonators (SRRs), as shown in Figure 6f.…”

“…Except the in-plane SRRs, the vertical SRRs out-of-plane also offer strong plasmon resonance with high Q-factor and low Ohmic losses [47]. In 2021, Li et al manufactured a vertical SRR utilizing three-dimensional printing technology [48]. The maximum value of the Q-factor occurring in the absorption peak at 0.797 THz is 152.9.…”

Microstructure-based high-quality factor terahertz metamaterial bio-detection sensor

“…Therefore, terahertz electromagnetic waves can be used in biomedical research to detect and identify biological macromolecules such as proteins, RNA, and DNA [20][21][22]. Furthermore, terahertz metamaterial bio-detection sensors based on microstructures [23][24] can be used as a new detection tool to improve the sensor detection resolution and to achieve high quality [25][26], rapid [27], and labelfree detection [28], which has good development potential in bio-detection.…”