Functionalized terahertz plasmonic metasensors: Femtomolar-level detection of SARS-CoV-2 spike proteins

• Published in: Biosensors & bioelectronics Vol. 177; p. 112971
• Main Authors: Ahmadivand, Arash, Gerislioglu, Burak, Ramezani, Zeinab, Kaushik, Ajeet, Manickam, Pandiaraj, Ghoreishi, S. Amir
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 01-04-2021
• Subjects: Antibodies, Immobilized - chemistry; Biosensing Techniques - methods; COVID-19 - diagnosis; COVID-19 - virology; COVID-19 pandemic; COVID-19 Serological Testing - methods; Femtomole-level detection; Gold - chemistry; Humans; Immunoassay - methods; Limit of Detection; Metal Nanoparticles - chemistry; SARS-CoV-2 - isolation & purification; SARS-CoV-2 spike protein; Spike Glycoprotein, Coronavirus - analysis; Terahertz plasmonic biosensors; Toroidal metasurfaces; COVID-19 pandemic; SARS-CoV-2 spike protein; Toroidal metasurfaces; Terahertz plasmonic biosensors; Femtomole-level detection
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2021.112971

Effective and efficient management of human betacoronavirus severe acute respiratory syndrome (SARS)-CoV-2 virus infection i.e., COVID-19 pandemic, required sensitive and selective sensors with short sample-to-result durations for performing desired diagnostics. In this direction, one appropriate alternative approach to detect SARS-CoV-2 virus protein at low level i.e., femtomolar (fM) is exploring plasmonic metasensor technology for COVID-19 diagnostics, which offers exquisite opportunities in advanced healthcare programs, and modern clinical diagnostics. The intrinsic merits of plasmonic metasensors stem from their capability to squeeze electromagnetic fields, simultaneously in frequency, time, and space. However, the detection of low-molecular weight biomolecules at low densities is a typical drawback of conventional metasensors that has recently been addressed using toroidal metasurface technology. This research is focused on the fabrication of a miniaturized plasmonic immunosensor based on toroidal electrodynamics concept that can sustain robustly confined plasmonic modes with ultranarrow lineshapes in the terahertz (THz) frequencies. By exciting toroidal dipole mode using our quasi-infinite metasurface and a judiciously optimized protocol based on functionalized gold nanoparticles (AuNPs) conjugated with the specific monoclonal antibody specific to spike protein (S1) of SARS-CoV-2 virus onto the metasurface, the resonance shifts for diverse concentrations of the spike protein are monitored. Possessing molecular weight around ~76 kDa allowed to detect the presence of SARS-CoV-2 virus protein with significantly low as limit of detection (LoD) was achieved as ~4.2 fM. We envisage that outcomes of this research will pave the way toward the use of toroidal metasensors as practical technologies for rapid and precise screening of SARS‐CoV‐2 virus carriers, symptomatic or asymptomatic, and spike proteins in hospitals, clinics, laboratories, and site of infection.
•Terahertz plasmonic metasensors for the detection of SARS-CoV-2 clinical diagnosis.•Quantitative and qualitative detection of spike proteins.•Rapid and precise detection of SARS-CoV-2 spike proteins at femtomolar concentrations.•Simple detection approach and compatible for high throughput COVID-19 screening in hospitals and test laboratories.•Early-stage detection of the infection through noninvasive tests.