ABSTRACT
Plasmonic metasurface biosensing has shown great potential in label-free detection of bio-nanoparticles with various sizes, such as cancer antigens, exosomes and SARS-CoV-2 virus. It typically relies on the immunoassay, but current studies usually neglect the perfect size matching between each target bio-nanoparticle and the surface near-field domain, which should be very critical for the enhancement of detection performance. In order to maximize the immunodetection capability for each bio-nanoparticle, we propose a plasmonic meta-biosensor based on the field-customized mechanism. Our design overcomes the serious interference of biofunctionalization and accomplishes a sensitivity of 27 times higher than the conventional nanoplasmonic counterpart. Our method also builds the important basis of single bio-nanoparticle immunodetection by a plasmonic metasurface. The customized plasmonic metasensing study implies a promising way towards ultra-low concentration biosensing or even single bio-nanoparticle detection for high-performance point-of-care-testing in the near future.
ABSTRACT
We present the design and analysis of a graphene metasurface-based cross polarization converter operating within the terahertz gap for detecting biomolecules over a broad spectral range, taking the SARS-CoV-2 virus as a specific example. To the best of our knowledge, our design reports the widest band of operation in the THz region of a graphene-based metasensor. Each meta-atom comprises a graphene pattern on silicon dioxide atop a continuous gold layer and exhibits near-unity cross polarization conversion ratio (PCR) and a 90% PCR bandwidth of 0.926 THz within the desired band (1.88 THz-2.81 THz). The proposed device demonstrates additional benefits which include a thin configuration (λ/7.84) and compact lattice size (λ/10.66), which are significantly better than other recently reported graphene metasurface biosensors. The device provides a sensitivity up to 490 GHz/RIU and a figure of merit (FoM) of 0.377 over a wide span of 0.926 THz within the terahertz gap. The electromagnetic response of this device has been validated via rigorous numerical analyses of simulated outputs as well as by developing a detailed circuit model representation of the same. The device demonstrates angular stability of nearly 40°under oblique incidence of the incident wave. IEEE
ABSTRACT
Plasmonic metasurfaces have been widely used in biosensing to improve the interaction between light and biomolecules through the effects of near-field confinement. When paired with biofunctionalization, plasmonic metasurface sensing is considered as a viable strategy for improving biomarker detection technologies. In this review, we enumerate the fundamental mechanism of plasmonic metasurfaces sensing and present their detection in human tumors and COVID-19. The advantages of rapid sampling, streamlined processes, high sensitivity, and easy accessibility are highlighted compared with traditional detection techniques. This review is looking forward to assisting scientists in advancing research and developing a new generation of multifunctional biosensors.
Subject(s)
Biosensing Techniques , COVID-19 , Neoplasms , Humans , SARS-CoV-2ABSTRACT
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.