Fast Methodology to Detect SARS-CoV-2 Antigen with Graphene FET

Extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the trigger behind the continuing COVID-19 pandemic, infecting tens of millions throughout the globe. Early analysis and administration of SARS-CoV-2 are essential for traceability, well timed remedy, and prevention of viral unfold.

Novel, Rapid Method to Detect SARS-CoV-2 S1 Antigen with Graphene FET​​​​​​​

​​​​​​​Research: Graphene-Based mostly Area-Impact Transistor for Ultrasensitive Immunosensing of SARS-CoV-2 Spike S1 Antigen. Picture Credit score: Leonid Altman/

In an article just lately revealed within the journal ACS Utilized Biomaterials, the researchers mentioned a novel speedy methodology to detect SARS-CoV-2 spike S1 antigen (S1-Ag) with excessive sensitivity utilizing a graphene-based field-effect transistor (FET).

The in-house developed anti-spike S1 antibody (S1-Ab) was immobilized covalently on the graphene. Furthermore, the graphene was surface-functionalized with carboxyl teams through carbodiimide chemistry.

Ultraviolet-visible (UV-vis) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, atomic drive microscopy (AFM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Raman spectroscopy, optical microscopy, enzyme-linked immunosorbent assays (ELISA) helped characterize the fabrication and bioconjugation technique of graphene-based FET.

{The electrical} response of the machine was correlated to the change in resistance precipitated due to real-time interplay between Ag–Ab. The graphene-based-FET units examined for S1-Ag, within the vary of 1-femtomolar to 1-micromolar revealed that the developed graphene-based-FET units have been extremely particular and delicate to even low ranges of S1-Ag

SARS-CoV-2 Detection Methods

The structural parts of the SARS-CoV-2 virus represent a single-stranded (ss) RNA, nucleocapsid (Nuc), spike (S), matrix (M), and envelope (E). SARS-CoV-2 has genomic similarity with bat coronavirus, RaTG13, and Center East respiratory syndrome (MERS-CoV). SARS-CoV-2 enters the host cell by means of angiotensin-converting enzyme II (ACE2), current in mammalian cells.

Reverse-transcriptase polymerase chain response (RT-PCR), lateral flow-based chromatographic strip, and chest computed tomography (CT) are the primary diagnostic methods for SARS-CoV-2 detection. Nevertheless, RT-PCR and CT scans are costly and time-delayed methods that require expert professionals for operation. Furthermore, viral detection through CT scan is non-specific to virus pressure and requires a excessive radiation dose. Therefore, a strong and delicate diagnostic method is required for viral Ag speedy detection.

Fluorine doped tin oxide (FTO)-based immunosensor is a SARS-CoV-2 detector with a restrict of detection (LOD) of 0.73 femtomoles. Biomolecules like enzymes, antibodies, aptamers, and nucleic acid are used to detect goal molecules. Nevertheless, antibodies are higher biorecognition parts over different DNA and aptamers on account of their excessive stability, excessive affinity, and immobilization on varied sensing parts like graphene.

A number of nanomaterials similar to iron oxide nanoparticles (NPs), gold (Au) NPs, organogels, carbon nanotubes, and graphene improve the biosensor’s sensitivity. Graphene is a hexagonal two-dimensional (2D) materials that’s preferable in comparison with nanomaterials in designing delicate biosensors. Furthermore, graphene-based FETs have nice potential for the event of diagnostic platforms. Though a number of FET-based sensors have been beforehand reported for SARS-CoV-2 detection, they’d refined fabrication necessities.

Graphene-based-FET for Immunosensing of SARS-CoV2 S1-Ab

Within the current research, the researchers generated an in-house S1-Ab modified graphene and developed a CoV-sensing FET machine to detect SARS-CoV-2 S1-Ab. The in-house generated S1-Abs within the current research made the sensor fabrication an economical methodology. Fabrication of graphene-based FETs was through silica (SiO2)/silicon (Si) substrate-based typical Scotch-tape exfoliation course of, adopted by electron beam lithography (EBL) and metallization with a 5/50 nanometers ratio of chromium (Cr)/Au, respectively.

The in-house generated S1-Ab have been conjugated covalently with graphene through carbodiimide chemistry. S1-Ab interplay with graphene-conjugated S1-Ab resulted within the native doping redistribution and consequently modified graphene’s resistance which is monitored. The fabrication and conjugation of Ab and Ag-Ab interactions have been confirmed utilizing varied analytical strategies.

The bioconjugation of S1-Ab on the floor of graphene confirmed two absorption peaks at 230 and 280 nanometers in UV-Vis spectroscopy, and the height at 280 nanometers corroborated the Ab peak. The FTIR spectra of the samples confirmed a broad peak round 3700-to-3000 -centimeter inverse, akin to the hydroxyl group (C−OH) stretching vibration, which is the attribute peak of activated graphene.

The outcomes demonstrated the fabrication of graphene-based-FET units to detect S1-Ag with an LOD of 10 femtomoles. This machine has a possible software in growing miniaturized and transportable sensors to detect SARS-CoV-2.


In conclusion, a graphene-based-FET sensor was developed, and the SARS-CoV-2 S1-Ab immobilized graphene was used as a sensing ingredient. Ag certain graphene-labeled Ab triggered the native doping redistribution that modified the conductivity in graphene, which was learn by the developed sensor. Ag proportion was analyzed with an LOD of 10 femtomoles.

The developed sensor machine was extremely particular to the SARS-CoV-2 virus and didn’t present cross-reactivity with MERS-CoV. Therefore, this sensor is an economical machine for SARS-CoV-2 detection, and the developed graphene-based-FET sensor has the potential to be miniaturized in growing a conveyable sensing platform to diagnose SARS-CoV-2.


Shahdeo, D., Chauhan, N., Majumdar, A., Ghosh, Arindam., Gandhi, Sonu. (2022). Graphene-Based mostly Area-Impact Transistor for Ultrasensitive Immunosensing of SARS-CoV-2 Spike S1 Antigen. ACS Utilized Biomaterials.

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