Table 3 Applications of the digital nucleic acid assay in detecting SARS-CoV-2
From: Microfluidics-based strategies for molecular diagnostics of infectious diseases
Compartmentalization methods | Analyte | Amplification methods | Performance | Detecting methods | References |
|---|---|---|---|---|---|
Crossflow/T-junction | SARS-CoV-2 ORF1ab, N and RNase P genes | RT-qPCR | 5 copies/test in 5Â min | Fluorescent probes | [164] |
Flow-focusing by QX200â„¢ Droplet Digitalâ„¢ PCR System, Bio-Rad (Pleasanton, California, U.S.) | SARS-CoV-2 ORF1ab, N and E genes | RT-qPCR | 2 copies/reaction in 4Â h | TaqMan Hydrolysis probe and EvaGreen | [165] |
Flow-focusing by QX200â„¢ Droplet Digitalâ„¢ PCR System | SARS-CoV-2 ORF1ab and N genes | RT-qPCR | 1.4 copies/reaction | TaqMan PCR reaction mixture | [157] |
By head-flattened pipette tips | SARA-CoV-2 ORF1ab and N genes | RT-qPCR | 3.8 copies/reaction in 1.5Â h | Thermo Scientific TaqMan 2019-nCoV Assay Kit v1 | [166] |
Flow-focusing by QX200â„¢ Droplet Digitalâ„¢ PCR System | SARS-CoV-2 RdRp and RNase P genes | RT-PCR | 2.9 copies /reaction | GeneFinderâ„¢ COVID-19 Plus RealAmp Kit, ELITech and Allplexâ„¢ 2019-nCoV Assay, Seegene | [167] |
SlipChip | SARS-CoV-2 NA extracted from the COVID-19 pseudo virus | LAMP | 344 copies/ml | LAMP fluorescent dye | [71] |
Microwell arrays | Synthetic SARS-CoV-2 targets | CRISPR-Cas13-based SHERLOCK technology | 10 copies/ml | Single-stranded DNA fluorogenic reporters | [158] |
By QuantStudio chips (ThermoFisher) with 0.7 nl digital reaction wells | SARS-CoV-2 N gene | CRISPR/Cas12a based RT-RPA | 1 GE/µl of SARS-CoV-2 RNA and 20 GE/µl of heat-inactivated SARS-CoV-2, qualitative detection in 15 min and quantitative detection in 30 min | Single-stranded DNA fluorogenic reporters | [169] |