Table 2.
Colorimetric assays developed for the detection of SARS-CoV-2.
| Type of detection | Target | Recognition element | Dynamic range | Limit of detection | References |
|---|---|---|---|---|---|
| Sandwich ELISA | UV-inactivated SARS-CoV-2 | Aptamer (SNAP1) and HRP anti-fluorescein antibody |
1 × 105 – 1 × 107 copies/mL | 5 × 105 copies/mL | (Kacherovsky et al., 2021) |
| ELONA | 2019-nCov-NP | Aptamer (N48 and N61) | 0 – 6 ng/mL | 93.75 pg/mL | (Tian et al., 2021) |
| Sandwich assay | Pseudotyped SARS-CoV-2 spiked in 50% saliva | MSA1 aptamer | 0 – 200 pM | 400 fM | (Li et al., 2021) |
| ELISA | Pseudotyped SARS-CoV-2 | C5-Fc-SS-biotin | 101 – 104 TCID50/mL | 16 TCID50/mL | (Girt et al., 2021) |
| Inactivated SARS-CoV-2 | C5-Fc-SS-biotin | 101 – 104 ffu/mL | 16 ffu/mL | ||
| Direct ELONA | SARS-COV-2 spike antigen | S14 aptamer | 0.5 – 125 nM | 2 nM | (Gupta et al., 2021) |
| Sandwich ELONA | SARS-CoV-2 S1 | Apt1T/Apt5B | 0.001 – 100 µg/mL | 21 ng/mL in buffer 15 ng/mL in VTM |
(Svobodova et al., 2021) |
| ELISA | SARS−CoV−2 S1 antigen | Monoclonal IgG antibody | 0 – 20 ng/mL | 1 ng/mL | (Mades et al., 2021) |
| Direct ELONA | SARS-CoV-2 S glycoprotein in buffer | CoV-RBD-1C | 0 – 5 μg/mL | 2.16 ng/mL | This study |
| SARS-CoV-2 S glycoprotein spiked in human nasal fluid | CoV-RBD-1C | 0 – 5 μg/mL | 1.02 ng/mL | This study | |
| Inactivated Alpha variant in buffer | CoV-RBD-1C | 5.32 × 101 – 5.32 × 105 TCID50/mL | 3.73 TCID50/mL | This study | |
| Inactivated Wuhan variant in buffer | CoV-RBD-1C | 6.20 × 101 – 6.20 × 105 TCID50/mL | 5.72 TCID50/mL | This study | |
| Inactivated Delta variant in buffer | CoV-RBD-1C | 6.45 × 101 – 6.45 × 105 TCID50/mL | 6.02 TCID50/mL | This study | |
| Sandwich ELONA | Inactivated Alpha variant in buffer | CoV-RBD-4C/CoV-RBD-1C | 5.32 × 101 – 5.32 × 105 TCID50/mL | 2.31 TCID50/mL | This study |
| Inactivated Wuhan variant in buffer | CoV-RBD-4C/CoV-RBD-1C | 6.20 × 101 – 6.20 × 105 TCID50/mL | 1.15 TCID50/mL | This study | |
| Inactivated Delta variant in buffer | CoV-RBD-4C/CoV-RBD-1C | 6.45 × 101 – 6.45 × 105 TCID50/mL | 2.96 TCID50/mL | This study | |
| Inactivated Alpha variant spiked in human nasal fluid | CoV-RBD-4C/CoV-RBD-1C | 5.32 × 101 – 5.32 × 105 TCID50/mL | 1.41 TCID50/mL | This study | |
| Inactivated Wuhan variant in human nasal fluid | CoV-RBD-4C/CoV-RBD-1C | 6.20 × 101 – 6.20 × 105 TCID50/mL | 1.79 TCID50/mL | This study |
UV, ultraviolet radiation; VTM, viral transport medium; NP, nucleocapsid protein; HRP, horse radish peroxidase; dynamic range, the range of analyte concentration tested.