Table 2.
Electrochemical biosensors for the detection of SARS-CoV-2
| Biosensing technique | Material selection and design | Biomarker | Limit of detection |
|---|---|---|---|
| Electrochemical impedance-based detector [59] | A 16-well container sensing electrodes and coated with 2.5 μg/mL of the RBD of SARS-CoV-2 spike protein | SARS-CoV-2 spike protein | It was not reported because of the hardware noise and variations in sample handling |
| Functionalized TiO2 Nanotube-Based Electrochemical Biosensor [60] | TiO2 nanotubes were synthesized by employing a low cost, simple, and one step electrochemical anodization of G1 grade titanium. Cobalt functionalization of the TiO2 nanotubes was also done by an incipient wetting method | SARS-CoV-2 spike protein | 0.7 nM |
| Antisense oligonucleotides directed electrochemical biosensor [61] | AuNPs-capped with specific antisense oligonucleotides (ssDNA) on a filter paper coated with graphene | SARS-CoV-2 viral RNA | 6.9 copies/μL |
| Graphene-based multiplexed telemedicine electrochemical biosensor [62] | Four graphene working electrodes, one graphene counter electrode, and one Ag/AgCl reference electrode patterned on a polyimide substrate | Nucleocapsid protein, IgM and IgG antibodies, and the inflammatory biomarker C-reactive protein (CRP) | - |
| Magnetic beads combined with carbon black-based screen-printed electrodes (a miniaturized electrochemical immunosensor) [63] | magnetic beads as support of immunological chain and secondary antibody with alkaline phosphatase as the immunological label; a three-electrode electrochemical cell including a graphite working electrode and counter electrode and a silver-based reference electrode | Spike (S) protein and nucleocapsid (N) protein | 19 ng/mL for spike protein and 8 ng/mL for nucleocapsid protein |
| Super sandwich-type electrochemical biosensor [64] | The CPs were immobilized on the surfaces of the Au@Fe3O4 nanoparticles to produce CP/Au@Fe3O4 nanocomposites. Then SCX8 was immobilized on the functionalized graphene (RGO), and Au@SCX8-TB-RGO-LP bioconjugate was produced. Finally, a CP-target-LP sandwich structure was fabricated. |
SARS-CoV-2 RNA (artificial and clinical samples) |
3 aM for artificial target and 200 copies/mL for clinical specimens |
| Novel printed circuit board-based electrochemical device [65] | FTO with gold nanoparticle (AuNPs). It was also immobilized by a nCovid-19 monoclonal antibody (nCovid-19Ab) | SARS-Cov-2 spike antigen | 10 fM |
| Field-effect transistor-based biosensor [30] | Graphene was coated on the SiO2/Si substrate. A coating of PMMA C4 was applied to the graphene layer. After transferring the PMMA/graphene layer to the SiO2/Si substrate, the PMMA layer was removed using acetone. A gold-chromium electrode layer was later fabricated on the etched graphene layer. | SARS-CoV-2 spike protein | 1 fg/mL (lower than the limit of detection of ELISA) |
| A field-effect transistor (Bio-FET)-based biosensor [66] | The graphene was soaked with a PBASE solution on the surface of the graphene FET biosensor. | SARS-CoV-2 spike protein | 1 fg/mL |
| Label-free graphene field-effect transistor (Gr-FET) biosensor [67] | The CVD method was employed to synthesize a single-crystal graphene layer on the single crystal copper. Functionalization of the graphene surface to bind the COVID-19 spike protein was carried out by immobilizing CSAb and ACE2 receptors on graphene's surface. During the incubation of the positively charged CSAB and negatively charged ACE2 in PBS buffer solution, negative and positive potentials were applied, respectively, to the graphene to enhance their immobilization on the surface of the graphene. | SARS-CoV-2 spike protein | 0.2 pM |